bindings: Add a macro for V8 Maybe<T> APIs.

Source/bindings/modules/v8/custom/V8CustomSQLStatementErrorCallback.cpp

Index: Source/bindings/modules/v8/custom/V8CustomSQLStatementErrorCallback.cpp
diff --git a/Source/bindings/modules/v8/custom/V8CustomSQLStatementErrorCallback.cpp b/Source/bindings/modules/v8/custom/V8CustomSQLStatementErrorCallback.cpp
index 36a1cd84a54b801ce7ba002aa278fb393462c9cd..0d5a50d456d10270b60af833c7770417acd44cd9 100644
--- a/Source/bindings/modules/v8/custom/V8CustomSQLStatementErrorCallback.cpp
+++ b/Source/bindings/modules/v8/custom/V8CustomSQLStatementErrorCallback.cpp
@@ -31,6 +31,7 @@
 #include "config.h"
 
 #include "bindings/core/v8/ScriptController.h"
+#include "bindings/core/v8/V8Binding.h"
 #include "bindings/modules/v8/V8SQLError.h"
 #include "bindings/modules/v8/V8SQLStatementErrorCallback.h"
 #include "bindings/modules/v8/V8SQLTransaction.h"
@@ -76,7 +77,11 @@ bool V8SQLStatementErrorCallback::handleEvent(SQLTransaction* transaction, SQLEr
     // statement, if any, or onto the next overall step otherwise. Otherwise,
     // the error callback did not return false, or there was no error callback.
     // Jump to the last step in the overall steps.
-    return exceptionCatcher.HasCaught() || (!result.IsEmpty() && result->BooleanValue());
+    if (exceptionCatcher.HasCaught())
+        return true;
+    bool value;
+    V8_MAYBE(value, result, BooleanValue(isolate->GetCurrentContext()), return false);

[haraken, 2015/03/11 02:43:21]

I guess this should be 'return true'.

It seems that this handleEvent wants to return false only when it succeeded in
the callback without causing any error and the result of the callback is true.
If that is the case, we want to return true when an empty handle is returned
from the callback. (Note: The only case where exceptionCatcher.HasCaught() is
false but an empty handle is returned is the case worker termination is
requested.)

[bashi, 2015/03/11 03:46:26]

Ah, right. Done.

+    return value;
 }
 
 } // namespace blink