Fix an out-of-boundary issue for wide string

fpdfsdk/src/jsapi/fxjs_v8.cpp

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
  
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #include "../../../core/include/fxcrt/fx_basic.h"
 #include "../../../core/include/fxcrt/fx_ext.h" 
 #include "../../include/jsapi/fxjs_v8.h"
 #include "../../include/fsdk_define.h"
@@ skipping 716 matching lines @@
 v8::Handle<v8::Object> JS_ToObject(v8::Handle<v8::Value> pValue)
 {
         if(pValue.IsEmpty()) return v8::Handle<v8::Object>();
         return pValue->ToObject();
 }
 
 CFX_WideString  JS_ToString(v8::Handle<v8::Value> pValue)
 {
         if(pValue.IsEmpty()) return L"";
         v8::String::Utf8Value s(pValue->ToString());
-        return CFX_WideString::FromUTF8(*s);
+        return CFX_WideString::FromUTF8(*s, s.length());

[palmer, 2014/07/10 19:10:55]

Ahh, I see, FromUTF8 has the same behavior. There are another 2 callers that
rely on the callee-must-assume behavior:

./fpdfsdk/src/javascript/Document.cpp:1073:                     CFX_WideString
wsKey  = CFX_WideString::FromUTF8(bsKey);

./core/src/fxcrt/fx_basic_util.cpp:276:    return
CFX_WideString::FromUTF8(rURI);

 }
 
 v8::Handle<v8::Array> JS_ToArray(v8::Handle<v8::Value> pValue)
 {
         if(pValue.IsEmpty()) return v8::Handle<v8::Array>();
         return v8::Handle<v8::Array>::Cast(pValue->ToObject());
 }
 
 void JS_ValueCopy(v8::Handle<v8::Value>& pTo, v8::Handle<v8::Value> pFrom)
 {
@@ skipping 286 matching lines @@
 {
         return d != d;
 }
 
 double JS_LocalTime(double d)
 {
         return JS_GetDateTime() + _getDaylightSavingTA(d);
 }
 
 //JavaScript time implement End.