Support Dart core libraries in source maps.

sdk/lib/_internal/pub/lib/src/dart.dart

Index: sdk/lib/_internal/pub/lib/src/dart.dart
diff --git a/sdk/lib/_internal/pub/lib/src/dart.dart b/sdk/lib/_internal/pub/lib/src/dart.dart
index 9e84360a24a67a59a4be60e1b020754f788c0bce..17162ce3fd497ede00d55389ae6fd1ff3b966d4a 100644
--- a/sdk/lib/_internal/pub/lib/src/dart.dart
+++ b/sdk/lib/_internal/pub/lib/src/dart.dart
@@ -18,7 +18,6 @@ import '../../../compiler/implementation/filenames.dart'
 
 import '../../asset/dart/serialize.dart';
 import 'io.dart';
-import 'sdk.dart' as sdk;
 import 'utils.dart';
 
 /// Interface to communicate with dart2js.
@@ -28,6 +27,12 @@ import 'utils.dart';
 /// [compiler.DiagnosticHandler] function types so that we can provide them
 /// as a single unit.
 abstract class CompilerProvider {
+  /// The URI to the root directory where "dart:" libraries can be found.
+  ///
+  /// This is used as the base URL to generate library URLs that are then sent
+  /// back to [provideInput].
+  Uri get libraryRoot;
+
   /// Given [uri], responds with a future that completes to the contents of
   /// the input file at that URI.
   ///
@@ -93,7 +98,7 @@ Future compile(String entrypoint, CompilerProvider provider, {
 
     return Chain.track(compiler.compile(
         path.toUri(entrypoint),
-        path.toUri(appendSlash(_libPath)),
+        provider.libraryRoot,
         path.toUri(appendSlash(packageRoot)),
         provider.provideInput,
         provider.handleDiagnostic,
@@ -103,15 +108,6 @@ Future compile(String entrypoint, CompilerProvider provider, {
   });
 }
 
-/// Returns the path to the directory containing the Dart core libraries.
-///
-/// This corresponds to the "sdk" directory in the repo and to the root of the
-/// compiled SDK.
-String get _libPath {
-  if (runningFromSdk) return sdk.rootDirectory;
-  return path.join(repoRoot, 'sdk');
-}
-
 /// Returns whether [dart] looks like an entrypoint file.
 bool isEntrypoint(CompilationUnit dart) {
   // Allow two or fewer arguments so that entrypoints intended for use with