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

src/ic/handler-compiler.h

 // Copyright 2014 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.
 
 #ifndef V8_IC_HANDLER_COMPILER_H_
 #define V8_IC_HANDLER_COMPILER_H_
 
 #include "src/ic/access-compiler.h"
 #include "src/ic/ic-state.h"
 
@@ skipping 205 matching lines @@
                                      Handle<JSObject> holder)
       : PropertyHandlerCompiler(isolate, Code::STORE_IC, map, holder,
                                 kCacheOnReceiver) {}
 
   virtual ~NamedStoreHandlerCompiler() {}
 
   Handle<Code> CompileStoreTransition(Handle<Map> transition,
                                       Handle<Name> name);
   Handle<Code> CompileStoreField(LookupIterator* it);
   Handle<Code> CompileStoreCallback(Handle<JSObject> object, Handle<Name> name,
-                                    Handle<AccessorInfo> callback);
+                                    Handle<AccessorInfo> callback,
+                                    LanguageMode language_mode);
   Handle<Code> CompileStoreCallback(Handle<JSObject> object, Handle<Name> name,
                                     const CallOptimization& call_optimization,
                                     int accessor_index);
   Handle<Code> CompileStoreViaSetter(Handle<JSObject> object, Handle<Name> name,
                                      int accessor_index,
                                      int expected_arguments);
   Handle<Code> CompileStoreInterceptor(Handle<Name> name);
 
   static void GenerateStoreViaSetter(MacroAssembler* masm, Handle<Map> map,
                                      Register receiver, Register holder,
@@ skipping 59 matching lines @@
   void CompileElementHandlers(MapHandleList* receiver_maps,
                               CodeHandleList* handlers,
                               LanguageMode language_mode);
 
   static void GenerateStoreSlow(MacroAssembler* masm);
 };
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_IC_HANDLER_COMPILER_H_