Disallow assignment to a top level method in dartc

compiler/java/com/google/dart/compiler/resolver/Resolver.java

Index: compiler/java/com/google/dart/compiler/resolver/Resolver.java
diff --git a/compiler/java/com/google/dart/compiler/resolver/Resolver.java b/compiler/java/com/google/dart/compiler/resolver/Resolver.java
index 745c0080484c74e2cfef17fef21b49f53645531d..242a84380bce479c383fbac35cf34523d79029f5 100644
--- a/compiler/java/com/google/dart/compiler/resolver/Resolver.java
+++ b/compiler/java/com/google/dart/compiler/resolver/Resolver.java
@@ -1583,11 +1583,17 @@ public class Resolver {
          case PARAMETER:
          case VARIABLE:
            if (lhs.getModifiers().isFinal()) {
-             topLevelContext.onError(node, ResolverErrorCode.CANNOT_ASSIGN_TO_FINAL, lhs.getName());
+             topLevelContext.onError(node.getArg1(), ResolverErrorCode.CANNOT_ASSIGN_TO_FINAL,
+                                     lhs.getName());
            }
            break;
+         case METHOD:
+           topLevelContext.onError(node.getArg1(),  ResolverErrorCode.CANNOT_ASSIGN_TO_METHOD,
+                                   lhs.getName());
+           break;
         }
       }
+
       return null;
     }