Roll dart to c688d0c. (flutter#6285)

* Roll dart to c688d0c.

Changes since last roll:
```
c688d0c [frontend] When serializing compiled expression proc, clone type params first.
346895e Choose the right platform in the command-line fasta tool in strong mode
51d5304 [frontend] Honor embedSourceText option in incremental compiler.
06792cb Remove StackListener.popList
69cd7cb [infra] Add compare_results.dart and update_flakiness.dart.
c3c4e63 Adjusted spec to use package syntax, thus eliminating bnf.sty
0315707 Add 'set' case to type_variable_conflict_test
00f2054 Add --repeat flag to test.py, so tests can be run multiple times
cf5cdea Add J/K versions CommonElements and ElementEnvironment
1681241 Remove _ClassEnsurer
a5b7181 Use json expectation files in dynamic tests
d560887 Fix TypeError in Observatory
867c527 Debugging dart in methods with dynamic type arguments
2e3f17f Add support for the new mixin syntax to supertype constraint checking and resynthesis.
929b2fb Adjust status file to account for CustomIsolates test passing now.
f0974ae Remove entry_points option from the test harness (should fix the precompiler bot failure).
296e4aa Split mixin_declaration_inference_valid_classes_test.dart into multiple tests.
2c427d3 Train the dartanalyzer on less source.
4127350 Detect references to instance variables without declared type.
a077609 Cleanup some of the build rules to not use Dart 1 mode.
3463f94 Delete any existing version of a DevFS file before overwriting the file
7763ec3 Surface analyzer toplevel inference limitations as DDC errors.
a386c07 [vm/aot] Add extra call specialization pass
8780174 Roll dart_style to 1.2.0.
a890d95 [vm/compiler] Avoid !(x>y) -> x<=y on fp operands.
bc79674 [vm/aot] Fix inferred type of implicitly initialized final fields
7df4900 Train the dartanalyzer tool on generating summaries.
80c1b88 Add copyright comments in resolution tests.
bbe4952 Cache mapping from subtypes names to files where they are subtyped.
cf67e40 Add test case reproducing issues flutter#34498 and flutter#34500.
81ce969 Enable implicit constructors with optional parameters in mixin applications.
cb33106 Compare AnalysisOptions signatures in analyzer_cli.
eb059a7 Keep analyzer-specific status entries together in language_2_analyzer.status
62ce86e Add --test-list and --repeat options to test.py, for deflaking
9e86c1a Normalize strong.status
3831da8 Include all problems in expectations
a1bd501 Make input validation optional
6fe2723 Tweak parameters of ProcessedOptions
0a5d7b8 Update status files after de984e5.
de984e5 Type checking for redirecting factories.
4134b95 [vm/tfa] Streamline handling of tear-offs in TFA
d44ffba [vm/tfa] Stop accepting non-empty entry points json files
30f0026 [VM runtime] Fix type test: C is a subtype of C<FutureOr> (fixes flutter#34482).
bbe8346 Test that type of the ListLiteral with two different enums is inferred.
37b41bd Update status files after d414815
d9fcaa3 Implement StreamTransformer.fromBind
abb392f add Pubspec.dependencyOverrides
c733ed7 firefix status for LayoutTests/fast/dom/Range/getClientRects-character_t01
d414815 Initial valid inference checks
dcabf2c Test for mixin declaration isObject and tweaks for error verifier.
```

* Update license

BUILD.gn

@@ -18,12 +18,6 @@ group("flutter") {
     public_deps += [ "$flutter_root/shell/testing" ]
   }
 
-  if (flutter_runtime_mode != "debug" &&
-      flutter_runtime_mode != "dynamic_profile" &&
-      flutter_runtime_mode != "dynamic_release") {
-    public_deps += [ "$flutter_root/lib/snapshot:entry_points_json_files" ]
-  }
-
   if (!is_fuchsia && !is_fuchsia_host) {
     if (current_toolchain == host_toolchain) {
       public_deps += [

DEPS

@@ -31,7 +31,7 @@ vars = {
   # Dart is: https://github.com/dart-lang/sdk/blob/master/DEPS.
   # You can use //tools/dart/create_updated_flutter_deps.py to produce
   # updated revision list of existing dependencies.
-  'dart_revision': '4eb879133a06c86869dc54cecf904f4b1d46c47b',
+  'dart_revision': 'c688d0c0c3ad3dece3a79ce0e115d787a94707ea',
 
   'dart_args_tag': '1.4.4',
   'dart_async_tag': '2.0.8',
@@ -46,7 +46,7 @@ vars = {
   'dart_crypto_tag': '2.0.6',
   'dart_csslib_tag': '0.14.4+1',
   'dart_dart2js_info_tag': '0.5.6+4',
-  'dart_dart_style_tag': '6f3efd209ff1828835936397b64be79265cc0c19',
+  'dart_dart_style_tag': '1.2.0',
   'dart_dartdoc_tag': 'v0.20.4',
   'dart_fixnum_tag': '0.10.8',
   'dart_glob_tag': '1.1.7',
@@ -115,7 +115,7 @@ allowed_hosts = [
 ]
 
 deps = {
-  'src': 'https://github.com/flutter/buildroot.git' + '@' + '7141218c62890635ce966e2530b465ea4c55c3e2',
+  'src': 'https://github.com/flutter/buildroot.git' + '@' + 'e191609670284e0d62ef2309d073b5586ac7d4a9',
 
    # Fuchsia compatibility
    #

ci/licenses_golden/licenses_third_party

@@ -1,4 +1,4 @@
-Signature: 5b5ec302d3f100a7ca4552f231d9f8b7
+Signature: dfbc023ceeca15d70ea76e125a481c0f
 
 UNUSED LICENSES:
 

lib/snapshot/BUILD.gn

@@ -5,7 +5,6 @@
 import("$flutter_root/lib/ui/dart_ui.gni")
 import("//build/compiled_action.gni")
 import("//third_party/dart/utils/compile_platform.gni")
-import("//third_party/dart/utils/generate_entry_points_json.gni")
 
 if (is_fuchsia) {
   import("//build/dart/dart_library.gni")
@@ -213,95 +212,3 @@ if (is_fuchsia || is_fuchsia_host) {
     ]
   }
 }
-
-# Template to generate entry points JSON file using gen_snapshot tool.
-# List of entry points is generated as a by-product while doing precompilation.
-#
-# This template expects the following arguments:
-#  - input: Name of the input dart script for precompilation.
-#  - output: Name of the output entry points JSON file.
-#  - extra_args: Extra arguments to pass to dart_bootstrap (optional).
-#  - extra_inputs: Extra input dependencies (optional).
-#
-template("generate_entry_points_json_with_gen_snapshot") {
-  assert(defined(invoker.input), "Must define input dart script")
-  assert(defined(invoker.output), "Must define output json file")
-  extra_args = []
-  if (defined(invoker.extra_args)) {
-    extra_args += invoker.extra_args
-  }
-  extra_inputs = []
-  if (defined(invoker.extra_inputs)) {
-    extra_inputs += invoker.extra_inputs
-  }
-  compiled_action(target_name) {
-    # Printing precompiler entry points is folded into precompilation, so gen_snapshot is invoked
-    # with correct arguments to generate app-aot snapshot.
-
-    input = invoker.input
-    output = invoker.output
-
-    tool = "//third_party/dart/runtime/bin:gen_snapshot"
-    inputs = [ input ] + extra_inputs
-    outputs = [
-      output,
-
-      # Though they are not consumed, GN needs to know to create the output directory.
-      "$target_gen_dir/dummy.vm_data.snapshot",
-      "$target_gen_dir/dummy.vm_instr.snapshot",
-      "$target_gen_dir/dummy.isolate_data.snapshot",
-      "$target_gen_dir/dummy.isolate_instr.snapshot",
-    ]
-    args = [
-             "--no-strong",
-             "--no-sync-async",
-             "--no-reify-generic-functions",
-             "--print-precompiler-entry-points=" + rebase_path(output),
-             "--snapshot-kind=app-aot-blobs",
-             "--vm_snapshot_data=" +
-                 rebase_path("$target_gen_dir/dummy.vm_data.snapshot"),
-             "--vm_snapshot_instructions=" +
-                 rebase_path("$target_gen_dir/dummy.vm_instr.snapshot"),
-             "--isolate_snapshot_data=" +
-                 rebase_path("$target_gen_dir/dummy.isolate_data.snapshot"),
-             "--isolate_snapshot_instructions=" +
-                 rebase_path("$target_gen_dir/dummy.isolate_instr.snapshot"),
-           ] + extra_args + [ rebase_path(input) ]
-  }
-}
-
-generate_entry_points_json_with_gen_snapshot("entry_points_json") {
-  input = "$flutter_root/lib/snapshot/snapshot.dart"
-  output = "$root_out_dir/dart_entry_points/entry_points.json"
-  dart_ui = "$flutter_root/lib/ui/ui.dart"
-  vmservice_io = "//third_party/dart/runtime/bin/vmservice/vmservice_io.dart"
-  dart_vm_entry_points_txt = "$flutter_root/runtime/dart_vm_entry_points.txt"
-  dart_io_entries_txt = "//third_party/dart/runtime/bin/dart_io_entries.txt"
-
-  extra_inputs = [
-    dart_ui,
-    vmservice_io,
-    dart_vm_entry_points_txt,
-    dart_io_entries_txt,
-  ]
-
-  extra_args = [
-    "--await_is_keyword",
-    "--url_mapping=dart:ui," + rebase_path(dart_ui),
-    "--url_mapping=dart:vmservice_io," + rebase_path(vmservice_io),
-    "--causal_async_stacks",
-    "--embedder_entry_points_manifest=" + rebase_path(dart_vm_entry_points_txt),
-    "--embedder_entry_points_manifest=" + rebase_path(dart_io_entries_txt),
-  ]
-}
-
-copy_entry_points_extra_json("entry_points_extra_json") {
-  output = "$root_out_dir/dart_entry_points/entry_points_extra.json"
-}
-
-group("entry_points_json_files") {
-  public_deps = [
-    ":entry_points_extra_json",
-    ":entry_points_json",
-  ]
-}