Make test of malformed types a dynamic type error.

sdk/lib/_internal/compiler/implementation/ssa/builder.dart

Index: sdk/lib/_internal/compiler/implementation/ssa/builder.dart
diff --git a/sdk/lib/_internal/compiler/implementation/ssa/builder.dart b/sdk/lib/_internal/compiler/implementation/ssa/builder.dart
index 2519c4fdbabce98ba7fd161277733ff3a47c273c..80486ab67fa0946852226211733a3b68e491bfb5 100644
--- a/sdk/lib/_internal/compiler/implementation/ssa/builder.dart
+++ b/sdk/lib/_internal/compiler/implementation/ssa/builder.dart
@@ -2910,13 +2910,16 @@ class SsaBuilder extends ResolvedVisitor implements Visitor {
     } else if ("as" == op.source) {
       visit(node.receiver);
       HInstruction expression = pop();
-      Node argument = node.arguments.head;
-      TypeAnnotation typeAnnotation = argument.asTypeAnnotation();
-      DartType type = elements.getType(typeAnnotation);
-      HInstruction converted = buildTypeConversion(
-          expression, type, HTypeConversion.CAST_TYPE_CHECK);
-      if (converted != expression) add(converted);
-      stack.add(converted);
+      DartType type = elements.getType(node.typeAnnotationFromIsCheckOrCast);
+      if (type.kind == TypeKind.MALFORMED_TYPE) {
+        ErroneousElement element = type.element;
+        generateTypeError(node, element.message);
+      } else {
+        HInstruction converted = buildTypeConversion(
+            expression, type, HTypeConversion.CAST_TYPE_CHECK);
+        if (converted != expression) add(converted);
+        stack.add(converted);
+      }
     } else {
       visit(node.receiver);
       visit(node.argumentsNode);
@@ -3021,6 +3024,11 @@ class SsaBuilder extends ResolvedVisitor implements Visitor {
       pushInvokeStatic(node, helper, inputs, backend.boolType);
       HInstruction call = pop();
       return new HIs.compound(type, expression, call, backend.boolType);
+    } else if (type.kind == TypeKind.MALFORMED_TYPE) {
+      ErroneousElement element = type.element;
+      generateTypeError(node, element.message);
+      HInstruction call = pop();
+      return new HIs.compound(type, expression, call, backend.boolType);
     } else {
       if (backend.hasDirectCheckFor(type)) {
         return new HIs.direct(type, expression, backend.boolType);