Revert "Prohibit importing from other module 'internal' dirs. (Polyme…

…rLabs#5999)" (PolymerLabs#6050)

This reverts commit 1d40e34.

tools/custom-loader.mjs

@@ -1,5 +1,4 @@
 import url from 'url';
-import path from 'path';
 
 export function resolve(specifier, parent, resolve) {
   if (!/^[./]/.test(specifier)) {
@@ -13,13 +12,6 @@ export function resolve(specifier, parent, resolve) {
       }
     }
   }
-  if (parent && parent.startsWith('file:///') && specifier.includes('/internal/')) {
-    const parentDir = path.dirname(parent.substr(7));  // 7 == len('file://')
-    const target = path.resolve(parentDir, specifier);
-    if (!target.startsWith(parentDir)) {
-      throw new Error(`cannot access internal file '${specifier}' from external location ${parent}`);
-    }
-  }
   if (!/\.(js|mjs)$/.test(specifier)) {
     if (/build/.test(parent)) {
       const resolved = new url.URL(specifier, parent || 'file:///');

tools/sigh.ts

@@ -391,7 +391,7 @@ function buildPath(path: string, preprocess: () => void): () => boolean {
       return false;
     }
 
-    if (!link(findProjectFiles('src', /webpack\.config\.js$/, /\.js$/))) {
+    if (!link(findProjectFiles('src', null, /\.js$/))) {
       console.error('build::link failed');
       return false;
     }

tsconfig.json

@@ -11,7 +11,9 @@
     "noErrorTruncation": true
   },
   "exclude": [
-    "src/tools/language-server/**/*",
-    "src/tools/vscode-language-client/**/*"
+    "build/**/*",
+    "cloud/**/*",
+    "./src/tools/language-server/**/*",
+    "./src/tools/vscode-language-client/**/*"
   ]
 }