[builtins] Fixed a Gcc compilation error in src/code-stub-assembler.cc.

src/code-stub-assembler.cc

 // Copyright 2016 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/code-stub-assembler.h"
 #include "src/code-factory.h"
 #include "src/frames-inl.h"
 #include "src/frames.h"
 #include "src/ic/handler-configuration.h"
 #include "src/ic/stub-cache.h"
@@ skipping 7888 matching lines @@
     Goto(&end);
   }
 
   Bind(&end);
   return var_result.value();
 }
 
 compiler::Node* CodeStubAssembler::CreateArrayIterator(
     compiler::Node* array, compiler::Node* array_map,
     compiler::Node* array_type, compiler::Node* context, IterationKind mode) {
-  int kBaseMapIndex;
+  int kBaseMapIndex = 0;
   switch (mode) {
     case IterationKind::kKeys:
       kBaseMapIndex = Context::TYPED_ARRAY_KEY_ITERATOR_MAP_INDEX;
       break;
     case IterationKind::kValues:
       kBaseMapIndex = Context::UINT8_ARRAY_VALUE_ITERATOR_MAP_INDEX;
       break;
     case IterationKind::kEntries:
       kBaseMapIndex = Context::UINT8_ARRAY_KEY_VALUE_ITERATOR_MAP_INDEX;
       break;
@@ skipping 148 matching lines @@
   Node* buffer_bit_field = LoadObjectField(
       buffer, JSArrayBuffer::kBitFieldOffset, MachineType::Uint32());
   Node* was_neutered_mask = Int32Constant(JSArrayBuffer::WasNeutered::kMask);
 
   return Word32NotEqual(Word32And(buffer_bit_field, was_neutered_mask),
                         Int32Constant(0));
 }
 
 }  // namespace internal
 }  // namespace v8