MalformedType used for all invalid type annotations.

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

Index: sdk/lib/_internal/compiler/implementation/compile_time_constants.dart
diff --git a/sdk/lib/_internal/compiler/implementation/compile_time_constants.dart b/sdk/lib/_internal/compiler/implementation/compile_time_constants.dart
index 975d4e510e16b9e3cf508dcee0246a52f3af35ec..0ac15099044b7911d906f218eff73773deb90479 100644
--- a/sdk/lib/_internal/compiler/implementation/compile_time_constants.dart
+++ b/sdk/lib/_internal/compiler/implementation/compile_time_constants.dart
@@ -133,7 +133,8 @@ class ConstantHandler extends CompilerTask {
             && element.isField()) {
           DartType elementType = element.computeType(compiler);
           DartType constantType = value.computeType(compiler);
-          if (!constantSystem.isSubtype(compiler, constantType, elementType)) {
+          if (elementType.isMalformed || constantType.isMalformed ||
+              !constantSystem.isSubtype(compiler, constantType, elementType)) {
             if (isConst) {
               MessageKind kind = MessageKind.NOT_ASSIGNABLE;
               compiler.reportError(node, new CompileTimeConstantError(
@@ -713,7 +714,8 @@ class ConstructorEvaluator extends CompileTimeConstantEvaluator {
       DartType constantType = constant.computeType(compiler);
       // TODO(ngeoffray): Handle type parameters.
       if (elementType.element.isTypeVariable()) return;
-      if (!constantSystem.isSubtype(compiler, constantType, elementType)) {
+      if (elementType.isMalformed || constantType.isMalformed ||
+          !constantSystem.isSubtype(compiler, constantType, elementType)) {
         MessageKind kind = MessageKind.NOT_ASSIGNABLE;
         compiler.reportError(node, new CompileTimeConstantError(
             kind, [elementType, constantType]));