Implement `in' for proxies.

src/runtime.cc

Index: src/runtime.cc
diff --git a/src/runtime.cc b/src/runtime.cc
index 0ce58366d2c5441734325fa79a9702eac56c6860..4bd6eb6fd0c9924496f2e48719a7069a3d735069 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -615,6 +615,14 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_GetHandler) {
 }
 
 
+RUNTIME_FUNCTION(MaybeObject*, Runtime_Fix) {
+  ASSERT(args.length() == 1);
+  CONVERT_CHECKED(JSProxy, proxy, args[0]);
+  proxy->Fix();
+  return proxy;
+}
+
+
 RUNTIME_FUNCTION(MaybeObject*, Runtime_ClassOf) {
   NoHandleAllocation ha;
   ASSERT(args.length() == 1);
@@ -4307,11 +4315,11 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_HasProperty) {
   NoHandleAllocation na;
   ASSERT(args.length() == 2);
 
-  // Only JS objects can have properties.
-  if (args[0]->IsJSObject()) {
-    JSObject* object = JSObject::cast(args[0]);
+  // Only JS receivers can have properties.
+  if (args[0]->IsJSReceiver()) {
+    JSReceiver* receiver = JSReceiver::cast(args[0]);
     CONVERT_CHECKED(String, key, args[1]);
-    if (object->HasProperty(key)) return isolate->heap()->true_value();
+    if (receiver->HasProperty(key)) return isolate->heap()->true_value();
   }
   return isolate->heap()->false_value();
 }