Implement sealing, freezing, and related functions for proxies.

src/runtime.cc

Index: src/runtime.cc
diff --git a/src/runtime.cc b/src/runtime.cc
index 0ce58366d2c5441734325fa79a9702eac56c6860..89b70cc2b86cdc726ca1abc8f00c0c9eb3dd2f5c 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);