Add type arguments to constants.

sdk/lib/_internal/compiler/implementation/elements/modelx.dart

Index: sdk/lib/_internal/compiler/implementation/elements/modelx.dart
diff --git a/sdk/lib/_internal/compiler/implementation/elements/modelx.dart b/sdk/lib/_internal/compiler/implementation/elements/modelx.dart
index 66f97f43cbcb1d81033b7101c7db17f374d42ea6..3d90f474348329da6ae6dbf1fa1eb2239fd5aa41 100644
--- a/sdk/lib/_internal/compiler/implementation/elements/modelx.dart
+++ b/sdk/lib/_internal/compiler/implementation/elements/modelx.dart
@@ -1253,6 +1253,19 @@ class FunctionElementX extends ElementX implements FunctionElement {
     return target;
   }
 
+  InterfaceType computeTargetType(Compiler compiler,
+                                  InterfaceType newType) {
+    if (!isRedirectingFactory) return newType;
+    ClassElement targetClass = getEnclosingClass();
+    TreeElements treeElements =
+        compiler.enqueuer.resolution.getCachedElements(
+            declaration);
+    FunctionExpression functionNode = parseNode(compiler);
+    Return redirectionNode = functionNode.body;
+    return treeElements.getType(redirectionNode.expression)
+        .subst(newType.typeArguments, targetClass.typeVariables);
+  }
+
   /**
    * Applies a patch function to this function. The patch function's body
    * is used as replacement when parsing this function's body.