Throw AbstractClassInstantiationError on abstract classes.

pkg/front_end/lib/src/fasta/target_implementation.dart

Index: pkg/front_end/lib/src/fasta/target_implementation.dart
diff --git a/pkg/front_end/lib/src/fasta/target_implementation.dart b/pkg/front_end/lib/src/fasta/target_implementation.dart
index 45a105f4ca7e466e2cbad8e196db6368a875a6c7..d702e6e7473b41879e437a776ef016c0f0500046 100644
--- a/pkg/front_end/lib/src/fasta/target_implementation.dart
+++ b/pkg/front_end/lib/src/fasta/target_implementation.dart
@@ -20,6 +20,7 @@ import 'translate_uri.dart' show TranslateUri;
 abstract class TargetImplementation extends Target {
   final TranslateUri uriTranslator;
   Builder cachedCompileTimeError;
+  Builder cachedAbstractClassInstantiationError;
   Builder cachedNativeAnnotation;
 
   TargetImplementation(Ticker ticker, this.uriTranslator) : super(ticker);
@@ -50,6 +51,18 @@ abstract class TargetImplementation extends Target {
         loader.coreLibrary.getConstructor("_CompileTimeError", isPrivate: true);
   }
 
+  /// Returns a reference to the constructor of
+  /// [AbstractClassInstantiationError] error.  The constructor is expected to
+  /// accept a single argument of type String, which is the name of the
+  /// abstract class.
+  Builder getAbstractClassInstantiationError(Loader loader) {
+    if (cachedAbstractClassInstantiationError != null) {
+      return cachedAbstractClassInstantiationError;
+    }
+    return cachedAbstractClassInstantiationError =
+        loader.coreLibrary.getConstructor("AbstractClassInstantiationError");
+  }
+
   /// Returns a reference to the constructor used for creating `native`
   /// annotations. The constructor is expected to accept a single argument of
   /// type String, which is the name of the native method.