[runtime] Support Proxy setPrototypeOf trap

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 38f5b7d503d8d2669058e4c580d6203f0f36500d..e5f80603fc06c13aa68d370f991ab4f3f6ad3a52 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -1030,7 +1030,7 @@ class Object {
 
 #define RETURN_FAILURE(isolate, should_throw, call) \
   do {                                              \
-    if ((should_throw) == DONT_THROW) {             \
+    if ((should_throw) == Object::DONT_THROW) {     \
       return Just(false);                           \
     } else {                                        \
       isolate->Throw(*isolate->factory()->call);    \
@@ -1172,7 +1172,8 @@ class Object {
 
   // ES6 section 7.3.9 GetMethod
   MUST_USE_RESULT static MaybeHandle<Object> GetMethod(
-      Handle<JSReceiver> receiver, Handle<Name> name);
+      Handle<JSReceiver> receiver, Handle<Name> name,
+      ShouldThrow should_throw = THROW_ON_ERROR);
 
   // ES6 section 12.5.6 The typeof Operator
   static Handle<String> TypeOf(Isolate* isolate, Handle<Object> object);
@@ -9578,7 +9579,11 @@ class JSProxy: public JSReceiver {
 
   DECLARE_CAST(JSProxy)
 
-  static MaybeHandle<Object> GetPrototype(Handle<JSProxy> receiver);
+  // Proxy Traps:
+  static MaybeHandle<Object> GetPrototype(Handle<JSProxy> proxy);
+  static Maybe<bool> SetPrototype(Handle<JSProxy> proxy, Handle<Object> value,
+                                  bool from_javascript,
+                                  ShouldThrow should_throw);
 
   MUST_USE_RESULT static MaybeHandle<Object> GetPropertyWithHandler(
       Handle<JSProxy> proxy,