Array length reduction should throw in strict mode if it can't delete an element.

src/ic/ic.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/ic/ic.h"
 
 #include "src/accessors.h"
 #include "src/api.h"
 #include "src/arguments.h"
 #include "src/base/bits.h"
 #include "src/codegen.h"
 #include "src/conversions.h"
 #include "src/execution.h"
 #include "src/frames-inl.h"
 #include "src/ic/call-optimization.h"
 #include "src/ic/handler-compiler.h"
 #include "src/ic/ic-inl.h"
 #include "src/ic/ic-compiler.h"
 #include "src/ic/stub-cache.h"
 #include "src/isolate-inl.h"
 #include "src/macro-assembler.h"
 #include "src/prototype.h"
 #include "src/runtime/runtime.h"
+#include "src/runtime/runtime-utils.h"
 
 namespace v8 {
 namespace internal {
 
 char IC::TransitionMarkFromState(IC::State state) {
   switch (state) {
     case UNINITIALIZED:
       return '0';
     case PREMONOMORPHIC:
       return '.';
@@ skipping 1706 matching lines @@
           TRACE_GENERIC_IC(isolate(), "StoreIC",
                            "special data property in prototype chain");
           break;
         }
         if (!AccessorInfo::IsCompatibleReceiverMap(isolate(), info,
                                                    receiver_map())) {
           TRACE_GENERIC_IC(isolate(), "StoreIC", "incompatible receiver type");
           break;
         }
         NamedStoreHandlerCompiler compiler(isolate(), receiver_map(), holder);
-        return compiler.CompileStoreCallback(receiver, lookup->name(), info);
+        return compiler.CompileStoreCallback(receiver, lookup->name(), info,
+                                             language_mode());
       } else if (accessors->IsAccessorPair()) {
         Handle<Object> setter(Handle<AccessorPair>::cast(accessors)->setter(),
                               isolate());
         if (!setter->IsJSFunction()) {
           TRACE_GENERIC_IC(isolate(), "StoreIC", "setter not a function");
           break;
         }
         Handle<JSFunction> function = Handle<JSFunction>::cast(setter);
         CallOptimization call_optimization(function);
         NamedStoreHandlerCompiler compiler(isolate(), receiver_map(), holder);
@@ skipping 1045 matching lines @@
   return *ic.ToBoolean(object);
 }
 
 
 RUNTIME_FUNCTION(Runtime_StoreCallbackProperty) {
   Handle<JSObject> receiver = args.at<JSObject>(0);
   Handle<JSObject> holder = args.at<JSObject>(1);
   Handle<HeapObject> callback_or_cell = args.at<HeapObject>(2);
   Handle<Name> name = args.at<Name>(3);
   Handle<Object> value = args.at<Object>(4);
+  CONVERT_LANGUAGE_MODE_ARG_CHECKED(language_mode, 5);
   HandleScope scope(isolate);
 
   Handle<AccessorInfo> callback(
       callback_or_cell->IsWeakCell()
           ? AccessorInfo::cast(WeakCell::cast(*callback_or_cell)->value())
           : AccessorInfo::cast(*callback_or_cell));
 
   DCHECK(callback->IsCompatibleReceiver(*receiver));
 
   Address setter_address = v8::ToCData<Address>(callback->setter());
   v8::AccessorNameSetterCallback fun =
       FUNCTION_CAST<v8::AccessorNameSetterCallback>(setter_address);
   DCHECK(fun != NULL);
 
   LOG(isolate, ApiNamedPropertyAccess("store", *receiver, *name));
+  Object::ShouldThrow should_throw =
+      is_sloppy(language_mode) ? Object::DONT_THROW : Object::THROW_ON_ERROR;
   PropertyCallbackArguments custom_args(isolate, callback->data(), *receiver,
-                                        *holder);
+                                        *holder, should_throw);
   custom_args.Call(fun, v8::Utils::ToLocal(name), v8::Utils::ToLocal(value));
   RETURN_FAILURE_IF_SCHEDULED_EXCEPTION(isolate);
   return *value;
 }
 
 
 /**
  * Attempts to load a property with an interceptor (which must be present),
  * but doesn't search the prototype chain.
  *
@@ skipping 126 matching lines @@
     KeyedLoadICNexus nexus(vector, vector_slot);
     KeyedLoadIC ic(IC::EXTRA_CALL_FRAME, isolate, &nexus);
     ic.UpdateState(receiver, key);
     ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, result, ic.Load(receiver, key));
   }
 
   return *result;
 }
 }  // namespace internal
 }  // namespace v8