Fix uninitialized variable compiler errors [GCC 4.8.4]

src/runtime/runtime-strings.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/arguments.h"
 #include "src/jsregexp-inl.h"
 #include "src/jsregexp.h"
 #include "src/runtime/runtime-utils.h"
@@ skipping 119 matching lines @@
 
 
 RUNTIME_FUNCTION(Runtime_StringIndexOf) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 3);
 
   CONVERT_ARG_HANDLE_CHECKED(String, sub, 0);
   CONVERT_ARG_HANDLE_CHECKED(String, pat, 1);
   CONVERT_ARG_HANDLE_CHECKED(Object, index, 2);
 
-  uint32_t start_index;
+  uint32_t start_index = 0;
   if (!index->ToArrayIndex(&start_index)) return Smi::FromInt(-1);
 
   RUNTIME_ASSERT(start_index <= static_cast<uint32_t>(sub->length()));
   int position = StringMatch(isolate, sub, pat, start_index);
   return Smi::FromInt(position);
 }
 
 
 template <typename schar, typename pchar>
 static int StringMatchBackwards(Vector<const schar> subject,
@@ skipping 30 matching lines @@
 
 
 RUNTIME_FUNCTION(Runtime_StringLastIndexOf) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 3);
 
   CONVERT_ARG_HANDLE_CHECKED(String, sub, 0);
   CONVERT_ARG_HANDLE_CHECKED(String, pat, 1);
   CONVERT_ARG_HANDLE_CHECKED(Object, index, 2);
 
-  uint32_t start_index;
+  uint32_t start_index = 0;
   if (!index->ToArrayIndex(&start_index)) return Smi::FromInt(-1);
 
   uint32_t pat_length = pat->length();
   uint32_t sub_length = sub->length();
 
   if (start_index + pat_length > sub_length) {
     start_index = sub_length - pat_length;
   }
 
   if (pat_length == 0) {
@@ skipping 1142 matching lines @@
 
 
 RUNTIME_FUNCTION(Runtime_StringGetLength) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 1);
   CONVERT_ARG_HANDLE_CHECKED(String, s, 0);
   return Smi::FromInt(s->length());
 }
 }  // namespace internal
 }  // namespace v8