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

pkg/compiler/lib/src/js_backend/runtime_types.dart

Index: pkg/compiler/lib/src/js_backend/runtime_types.dart
diff --git a/pkg/compiler/lib/src/js_backend/runtime_types.dart b/pkg/compiler/lib/src/js_backend/runtime_types.dart
index 8aefed6ca006671cf2abbaf852ee65ef96b5cb74..349905aeaad67b8ec99d4e83f90d705aac0f3381 100644
--- a/pkg/compiler/lib/src/js_backend/runtime_types.dart
+++ b/pkg/compiler/lib/src/js_backend/runtime_types.dart
@@ -680,7 +680,9 @@ class TypeRepresentationGenerator extends DartTypeVisitor {
       properties.add(new jsAst.Property(js.string(name), value));
     }
 
-    addProperty(namer.functionTypeTag, js.string(''));
+    // Type representations for functions have a property which is a tag marking
+    // them as function types. The value is not used, so '1' is just a dummy.
+    addProperty(namer.functionTypeTag, js.number(1));
     if (type.returnType.isVoid) {
       addProperty(namer.functionTypeVoidReturnTag, js('true'));
     } else if (!type.returnType.treatAsDynamic) {