Remove use of Element in ResolutionEnqueuerListener.

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

Index: pkg/compiler/lib/src/elements/types.dart
diff --git a/pkg/compiler/lib/src/elements/types.dart b/pkg/compiler/lib/src/elements/types.dart
index d3f68833485e7a8b3d9b3bff99b7d8632f8d7edf..f169ef21f0e43b360f7e1573e7c8f30377859aaf 100644
--- a/pkg/compiler/lib/src/elements/types.dart
+++ b/pkg/compiler/lib/src/elements/types.dart
@@ -59,6 +59,9 @@ abstract class DartType {
 
   /// Is `true` if this type is a malformed type.
   bool get isMalformed => false;
+
+  /// Whether this type contains a type variable.
+  bool get containsTypeVariables => false;
 }
 
 class InterfaceType extends DartType {
@@ -67,6 +70,9 @@ class InterfaceType extends DartType {
 
   InterfaceType(this.element, this.typeArguments);
 
+  bool get containsTypeVariables =>
+      typeArguments.any((type) => type.containsTypeVariables);
+
   int get hashCode {
     int hash = element.hashCode;
     for (DartType argument in typeArguments) {
@@ -108,6 +114,8 @@ class TypeVariableType extends DartType {
 
   bool get isTypeVariable => true;
 
+  bool get containsTypeVariables => true;
+
   int get hashCode => 17 * element.hashCode;
 
   bool operator ==(other) {
@@ -161,6 +169,13 @@ class FunctionType extends DartType {
       this.namedParameters,
       this.namedParameterTypes);
 
+  bool get containsTypeVariables {
+    return returnType.containsTypeVariables ||
+        parameterTypes.any((type) => type.containsTypeVariables) ||
+        optionalParameterTypes.any((type) => type.containsTypeVariables) ||
+        namedParameterTypes.any((type) => type.containsTypeVariables);
+  }
+
   bool get isFunctionType => true;
 
   int get hashCode {