Fix assertion failure in ScriptRegexp::match

Source/bindings/core/v8/ScriptRegexp.cpp

 /*
  * Copyright (C) 2004, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Collabora Ltd.
  * Copyright (C) 2011 Peter Varga (pvarga@webkit.org), University of Szeged
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
@@ skipping 15 matching lines @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "config.h"
 #include "bindings/core/v8/ScriptRegexp.h"
 
 #include "bindings/core/v8/V8Binding.h"
 #include "bindings/core/v8/V8PerIsolateData.h"
 #include "bindings/core/v8/V8ScriptRunner.h"
 #include "platform/ScriptForbiddenScope.h"
+#include "wtf/Optional.h"
 
 namespace blink {
 
 ScriptRegexp::ScriptRegexp(const String& pattern, TextCaseSensitivity caseSensitivity, MultilineMode multilineMode)
 {
     v8::Isolate* isolate = v8::Isolate::GetCurrent();
     v8::HandleScope handleScope(isolate);
     v8::Local<v8::Context> context = V8PerIsolateData::from(isolate)->ensureScriptRegexpContext();
     v8::Context::Scope contextScope(context);
     v8::TryCatch tryCatch;
@@ skipping 14 matching lines @@
     if (matchLength)
         *matchLength = 0;
 
     if (m_regex.isEmpty() || string.isNull())
         return -1;
 
     // v8 strings are limited to int.
     if (string.length() > INT_MAX)
         return -1;
 
-    ScriptForbiddenScope::AllowUserAgentScript allowScript;
+    Optional<ScriptForbiddenScope::AllowUserAgentScript> allowScript;
+    if (isMainThread())
+        allowScript.emplace();

[haraken, 2015/08/27 23:46:40]

Would it make sense to move the Optional into AllowUserAgentScript and make this
the default behavior of AllowUserAgentScript?

[yurys, 2015/08/27 23:56:49]

Done. I'm not sure what was the reason to have all this machinery only on the
main thread.

 
     v8::Isolate* isolate = v8::Isolate::GetCurrent();
     v8::HandleScope handleScope(isolate);
     v8::Local<v8::Context> context = V8PerIsolateData::from(isolate)->ensureScriptRegexpContext();
     v8::Context::Scope contextScope(context);
     v8::TryCatch tryCatch;
 
     v8::Local<v8::RegExp> regex = m_regex.newLocal(isolate);
     v8::Local<v8::Value> exec;
     if (!regex->Get(context, v8AtomicString(isolate, "exec")).ToLocal(&exec))
@@ skipping 22 matching lines @@
         v8::Local<v8::Value> match;
         if (!result->Get(context, 0).ToLocal(&match))
             return -1;
         *matchLength = match.As<v8::String>()->Length();
     }
 
     return matchOffset.As<v8::Int32>()->Value() + startFrom;
 }
 
 } // namespace blink