Revert of GC plugin: improve error reporting when tracing illegal fields.

tools/clang/blink_gc_plugin/Config.h

Index: tools/clang/blink_gc_plugin/Config.h
diff --git a/tools/clang/blink_gc_plugin/Config.h b/tools/clang/blink_gc_plugin/Config.h
index 8f494bbf2184a4cdefd9400d3d4ab1026870e626..53e52214de15e49915a854ca95c85bb8e4c984a6 100644
--- a/tools/clang/blink_gc_plugin/Config.h
+++ b/tools/clang/blink_gc_plugin/Config.h
@@ -49,13 +49,12 @@
   }
 
   static bool IsPersistent(const std::string& name) {
-    return name == "Persistent" ||
-           name == "WeakPersistent" ;
-  }
-
-  static bool IsCrossThreadPersistent(const std::string& name) {
-    return name == "CrossThreadPersistent" ||
-           name == "CrossThreadWeakPersistent" ;
+    return name == "Persistent";
+  }
+
+  static bool IsPersistentHandle(const std::string& name) {
+    return IsPersistent(name) ||
+           IsPersistentGCCollection(name);
   }
 
   static bool IsRefPtr(const std::string& name) {
@@ -64,10 +63,6 @@
 
   static bool IsOwnPtr(const std::string& name) {
     return name == "OwnPtr";
-  }
-
-  static bool IsUniquePtr(const std::string& name) {
-    return name == "unique_ptr";
   }
 
   static bool IsWTFCollection(const std::string& name) {