Fix uninitialized variable compiler errors [GCC 4.8.4]

src/runtime/runtime-scopes.cc

 // 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.
 
 #include "src/v8.h"
 
 #include "src/accessors.h"
 #include "src/arguments.h"
 #include "src/frames-inl.h"
 #include "src/messages.h"
@@ skipping 1045 matching lines @@
   // Compute the frame holding the arguments.
   JavaScriptFrameIterator it(isolate);
   it.AdvanceToArgumentsFrame();
   JavaScriptFrame* frame = it.frame();
 
   // Get the actual number of provided arguments.
   const uint32_t n = frame->ComputeParametersCount();
 
   // Try to convert the key to an index. If successful and within
   // index return the the argument from the frame.
-  uint32_t index;
+  uint32_t index = 0;
   if (raw_key->ToArrayIndex(&index) && index < n) {
     return frame->GetParameter(index);
   }
 
   HandleScope scope(isolate);
   if (raw_key->IsSymbol()) {
     Handle<Symbol> symbol = Handle<Symbol>::cast(raw_key);
     if (Name::Equals(symbol, isolate->factory()->iterator_symbol())) {
       return isolate->native_context()->array_values_iterator();
     }
@@ skipping 56 matching lines @@
   return Smi::FromInt(frame->GetArgumentsLength());
 }
 
 
 RUNTIME_FUNCTION(Runtime_Arguments) {
   SealHandleScope shs(isolate);
   return __RT_impl_Runtime_GetArgumentsProperty(args, isolate);
 }
 }  // namespace internal
 }  // namespace v8