Check function type equivalence

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 c5612a72201b3ad9e970599af6859c463fd039a1..709407c30f5e1c892b60910997192fae637a2ce0 100644
--- a/pkg/compiler/lib/src/elements/modelx.dart
+++ b/pkg/compiler/lib/src/elements/modelx.dart
@@ -2648,7 +2648,8 @@ class SynthesizedConstructorElementX extends ConstructorElementX {
       : super('', ElementKind.GENERATIVE_CONSTRUCTOR, Modifiers.EMPTY,
             enclosing) {
     functionSignature = new FunctionSignatureX(
-        type: new ResolutionFunctionType.synthesized(enclosingClass.thisType));
+        type: new ResolutionFunctionType.synthesized(
+            const ResolutionDynamicType()));
     _resolvedAst =
         new SynthesizedResolvedAst(this, ResolvedAstKind.DEFAULT_CONSTRUCTOR);
   }