Move computeType to TypedElement and TypeDeclarationElement.

pkg/compiler/lib/src/elements/modelx.dart

Index: pkg/compiler/lib/src/elements/modelx.dart
diff --git a/pkg/compiler/lib/src/elements/modelx.dart b/pkg/compiler/lib/src/elements/modelx.dart
index 964cb741f3ed68b3d23340319d8c771fd1c40845..a33e523ca491fc412cb7a0d20394ea597f4b6876 100644
--- a/pkg/compiler/lib/src/elements/modelx.dart
+++ b/pkg/compiler/lib/src/elements/modelx.dart
@@ -67,12 +67,6 @@ abstract class ElementX extends Element with ElementCommon {
     return null;
   }
 
-  DartType computeType(Compiler compiler) {
-    compiler.internalError(this,
-        "computeType not implemented on $this.");
-    return null;
-  }
-
   void addMetadata(MetadataAnnotationX annotation) {
     assert(annotation.annotatedElement == null);
     annotation.annotatedElement = this;
@@ -302,6 +296,7 @@ class ErroneousElementX extends ElementX implements ErroneousElement {
   bool get isRedirectingFactory => unsupported();
 
   computeSignature(compiler) => unsupported();
+  computeType(compiler) => unsupported();
 
   bool get hasFunctionSignature => false;