Add Ahem as a test font in CanvasKit mode (flutter#27652)

* Add Ahem as a test font in CanvasKit mode

* Don't enable `debugEmulateFlutterDriver` by default since tests use
platform channels.

* Update goldens lock

lib/web_ui/dev/goldens_lock.yaml

@@ -1,2 +1,2 @@
 repository: https://github.com/flutter/goldens.git
-revision: 364782e0e6afb9e977524395c4376916340bf176
+revision: f1baad46498ce1a754a15d02249827bb042b446b

lib/web_ui/lib/src/engine/canvaskit/fonts.dart

@@ -19,6 +19,9 @@ import 'font_fallbacks.dart';
 const String _robotoUrl =
     'https://fonts.gstatic.com/s/roboto/v20/KFOmCnqEu92Fr1Me5WZLCzYlKw.ttf';
 
+// URL for the Ahem font, only used in tests.
+const String _ahemUrl = 'packages/ui/assets/ahem.ttf';
+
 /// Manages the fonts used in the Skia-based backend.
 class SkiaFontCollection {
   /// Fonts that have been registered but haven't been loaded yet.
@@ -47,7 +50,8 @@ class SkiaFontCollection {
           .add(SkFont(font.typeface));
     }
 
-    for (RegisteredFont font in FontFallbackData.instance.registeredFallbackFonts) {
+    for (RegisteredFont font
+        in FontFallbackData.instance.registeredFallbackFonts) {
       fontProvider!.registerFont(font.bytes, font.family);
       familyToFontMap
           .putIfAbsent(font.family, () => <SkFont>[])
@@ -139,6 +143,11 @@ class SkiaFontCollection {
     }
   }
 
+  Future<void> debugRegisterTestFonts() async {
+    _unloadedFonts.add(_registerFont(_ahemUrl, 'Ahem'));
+    FontFallbackData.instance.globalFontFallbacks.add('Ahem');
+  }
+
   Future<RegisteredFont?> _registerFont(String url, String family) async {
     ByteBuffer buffer;
     try {
@@ -162,7 +171,8 @@ class SkiaFontCollection {
   }
 
   String? _readActualFamilyName(Uint8List bytes) {
-    final SkFontMgr tmpFontMgr = canvasKit.FontMgr.FromData(<Uint8List>[bytes])!;
+    final SkFontMgr tmpFontMgr =
+        canvasKit.FontMgr.FromData(<Uint8List>[bytes])!;
     final String? actualFamily = tmpFontMgr.getFamilyName(0);
     tmpFontMgr.delete();
     return actualFamily;

lib/web_ui/lib/src/ui/initialization.dart

@@ -7,7 +7,8 @@ part of ui;
 Future<void> webOnlyInitializePlatform({
   engine.AssetManager? assetManager,
 }) {
-  final Future<void> initializationFuture = _initializePlatform(assetManager: assetManager);
+  final Future<void> initializationFuture =
+      _initializePlatform(assetManager: assetManager);
   scheduleMicrotask(() {
     // Access [engine.lineLookup] to force the lazy unpacking of line break data
     // now. Removing this line won't break anything. It's just an optimization
@@ -46,7 +47,8 @@ engine.FontCollection? _fontCollection;
 bool _webOnlyIsInitialized = false;
 bool get webOnlyIsInitialized => _webOnlyIsInitialized;
 Future<void> webOnlySetAssetManager(engine.AssetManager assetManager) async {
-  assert(assetManager != null, 'Cannot set assetManager to null'); // ignore: unnecessary_null_comparison
+  assert(assetManager != null,
+      'Cannot set assetManager to null'); // ignore: unnecessary_null_comparison
   if (assetManager == _assetManager) {
     return;
   }
@@ -68,18 +70,24 @@ Future<void> webOnlySetAssetManager(engine.AssetManager assetManager) async {
     }
   }
 
-  if (debugEmulateFlutterTesterEnvironment && !engine.useCanvasKit) {
-    _fontCollection!.debugRegisterTestFonts();
+  if (debugEmulateFlutterTesterEnvironment) {
+    if (engine.useCanvasKit) {
+      engine.skiaFontCollection.debugRegisterTestFonts();
+    } else {
+      _fontCollection!.debugRegisterTestFonts();
+    }
   }
 }
 
-bool get debugEmulateFlutterTesterEnvironment => _debugEmulateFlutterTesterEnvironment;
+bool get debugEmulateFlutterTesterEnvironment =>
+    _debugEmulateFlutterTesterEnvironment;
 
 set debugEmulateFlutterTesterEnvironment(bool value) {
   _debugEmulateFlutterTesterEnvironment = value;
   if (_debugEmulateFlutterTesterEnvironment) {
     const Size logicalSize = Size(800.0, 600.0);
-    engine.window.webOnlyDebugPhysicalSizeOverride = logicalSize * window.devicePixelRatio;
+    engine.window.webOnlyDebugPhysicalSizeOverride =
+        logicalSize * window.devicePixelRatio;
   }
 }