Merge CoreTypes and CoreClasses into CommonElements.

tests/compiler/dart2js/simple_inferrer_test.dart

Index: tests/compiler/dart2js/simple_inferrer_test.dart
diff --git a/tests/compiler/dart2js/simple_inferrer_test.dart b/tests/compiler/dart2js/simple_inferrer_test.dart
index 08b5620767a844a2b526244cf5d491c5906b0461..fb5467451209ebe7f0b96eeb3285968d9b6df0ec 100644
--- a/tests/compiler/dart2js/simple_inferrer_test.dart
+++ b/tests/compiler/dart2js/simple_inferrer_test.dart
@@ -761,7 +761,7 @@ void main() {
         checkReturn('returnEmpty1', const TypeMask.nonNullEmpty());
         checkReturn('returnEmpty2', const TypeMask.nonNullEmpty());
         TypeMask intType = new TypeMask.nonNullSubtype(
-            compiler.coreClasses.intClass, closedWorld);
+            compiler.commonElements.intClass, closedWorld);
         checkReturn('testIsCheck1', intType);
         checkReturn('testIsCheck2', intType);
         checkReturn('testIsCheck3', intType.nullable());
@@ -796,7 +796,7 @@ void main() {
         checkReturn(
             'returnAsString',
             new TypeMask.subtype(
-                compiler.coreClasses.stringClass, closedWorld));
+                compiler.commonElements.stringClass, closedWorld));
         checkReturn('returnIntAsNum', commonMasks.uint31Type);
         checkReturn('returnAsTypedef', commonMasks.functionType.nullable());
         checkReturn('returnTopLevelGetter', commonMasks.uint31Type);