Make computeSignature private to modelx.

pkg/compiler/lib/src/resolution/enum_creator.dart

Index: pkg/compiler/lib/src/resolution/enum_creator.dart
diff --git a/pkg/compiler/lib/src/resolution/enum_creator.dart b/pkg/compiler/lib/src/resolution/enum_creator.dart
index 70099860c3323e308d0082443a0e749482a193ba..127833d8aa9b1a32cdcade1b357ed057caff0378 100644
--- a/pkg/compiler/lib/src/resolution/enum_creator.dart
+++ b/pkg/compiler/lib/src/resolution/enum_creator.dart
@@ -233,7 +233,7 @@ class EnumCreator {
         requiredParameterCount: 1,
         type: new FunctionType(constructor, const VoidType(),
             <DartType>[intType]));
-    constructor.functionSignatureCache = constructorSignature;
+    constructor.functionSignature = constructorSignature;
     enumClass.addMember(constructor, reporter);
 
     List<FieldElement> enumValues = <FieldElement>[];
@@ -304,7 +304,7 @@ class EnumCreator {
         enumClass, Modifiers.EMPTY, toStringNode);
     FunctionSignatureX toStringSignature = new FunctionSignatureX(
         type: new FunctionType(toString, stringType));
-    toString.functionSignatureCache = toStringSignature;
+    toString.functionSignature = toStringSignature;
     enumClass.addMember(toString, reporter);
 
     enumClass.enumValues = enumValues;