Implement LibraryMirror.metadata.

dart/sdk/lib/_internal/compiler/implementation/compiler.dart

Index: dart/sdk/lib/_internal/compiler/implementation/compiler.dart
diff --git a/dart/sdk/lib/_internal/compiler/implementation/compiler.dart b/dart/sdk/lib/_internal/compiler/implementation/compiler.dart
index f14543f3dcae2b23c108967dfbc57f81277b579e..0c8865f49fddc61f004517dfa672a0abd1f0dd49 100644
--- a/dart/sdk/lib/_internal/compiler/implementation/compiler.dart
+++ b/dart/sdk/lib/_internal/compiler/implementation/compiler.dart
@@ -643,6 +643,7 @@ abstract class Compiler implements DiagnosticListener {
     }
     if (uri == Uri.parse('dart:mirrors')) {
       mirrorSystemClass = library.find(const SourceString('MirrorSystem'));
+      metadataHandler = constantHandler;
     } else if (uri == Uri.parse('dart:_collection-dev')) {
       symbolImplementationClass = library.find(const SourceString('Symbol'));
     }
@@ -822,6 +823,7 @@ abstract class Compiler implements DiagnosticListener {
     // Elements required by enqueueHelpers are global dependencies
     // that are not pulled in by a particular element.
     backend.enqueueHelpers(enqueuer.resolution, globalDependencies);
+    resolveReflectiveDataIfNeeded();
     processQueue(enqueuer.resolution, main);
     enqueuer.resolution.logSummary(log);
 
@@ -864,6 +866,17 @@ abstract class Compiler implements DiagnosticListener {
     checkQueues();
   }
 
+  void resolveReflectiveDataIfNeeded() {
+    // Only need reflective data when dart:mirrors is loaded.
+    if (mirrorSystemClass == null) return;
+
+    for (LibraryElement library in libraries.values) {
+      for (Link link = library.metadata; !link.isEmpty; link = link.tail) {
+        link.head.ensureResolved(this);
+      }
+    }
+  }
+
   void fullyEnqueueLibrary(LibraryElement library) {
     library.forEachLocalMember(fullyEnqueueTopLevelElement);
   }