dart2js: create a 'types' table for each deferred unit.

pkg/compiler/lib/src/js_emitter/metadata_collector.dart

Index: pkg/compiler/lib/src/js_emitter/metadata_collector.dart
diff --git a/pkg/compiler/lib/src/js_emitter/metadata_collector.dart b/pkg/compiler/lib/src/js_emitter/metadata_collector.dart
index 9876dacd6ace666e315f5468244f61204c14c3fb..48df1396d7382af53e862e07d1ea95a544a56915 100644
--- a/pkg/compiler/lib/src/js_emitter/metadata_collector.dart
+++ b/pkg/compiler/lib/src/js_emitter/metadata_collector.dart
@@ -15,12 +15,13 @@ class MetadataCollector {
   /// A map used to canonicalize the entries of globalMetadata.
   final Map<String, int> _globalMetadataMap = <String, int>{};
 
-  /// A list of JS expression representing types including function types and
-  /// typedefs.
-  final List<String> types = <String>[];
+  /// A map with lists of JS expressions, one list for each output unit. The
+  /// entries represent types including function types and typedefs.
+  final Map<OutputUnit, List<String>> types = <OutputUnit, List<String>>{};
 
   /// A map used to canonicalize the entries of types.
-  final Map<String, int> _typesMap = <String, int>{};
+  final Map<OutputUnit, Map<String, int>> _typesMap =
+      <OutputUnit, Map<String, int>>{};
 
   MetadataCollector(this._compiler, this._emitter);
 
@@ -91,6 +92,11 @@ class MetadataCollector {
   }
 
   int reifyType(DartType type) {
+    return reifyTypeForOutputUnit(type,
+                                  _compiler.deferredLoadTask.mainOutputUnit);
+  }
+
+  int reifyTypeForOutputUnit(DartType type, OutputUnit outputUnit) {
     jsAst.Expression representation =
         _backend.rti.getTypeRepresentation(
             type,
@@ -103,8 +109,8 @@ class MetadataCollector {
               return _backend.isAccessibleByReflection(typedef.element);
             });
 
-    return addType(
-        jsAst.prettyPrint(representation, _compiler).getText());
+    return addTypeInOutputUnit(
+        jsAst.prettyPrint(representation, _compiler).getText(), outputUnit);
   }
 
   int reifyName(String name) {
@@ -118,10 +124,17 @@ class MetadataCollector {
     });
   }
 
-  int addType(String compiledType) {
-    return _typesMap.putIfAbsent(compiledType, () {
-      types.add(compiledType);
-      return types.length - 1;
+  int addTypeInOutputUnit(String compiledType, OutputUnit outputUnit) {
+    if (_typesMap[outputUnit] == null) {
+      _typesMap[outputUnit] = <String, int>{};
+    }
+    return _typesMap[outputUnit].putIfAbsent(compiledType, () {
+
+      if (types[outputUnit] == null)
+        types[outputUnit] = <String>[];
+
+      types[outputUnit].add(compiledType);
+      return types[outputUnit].length - 1;
     });
   }