Fix memory leaks caused by PromiseRejectionEvents

Source/bindings/core/v8/RejectedPromises.cpp

 // Copyright 2015 The Chromium 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 "config.h"
 #include "bindings/core/v8/RejectedPromises.h"
 
 #include "bindings/core/v8/ScopedPersistent.h"
 #include "bindings/core/v8/ScriptState.h"
 #include "bindings/core/v8/ScriptValue.h"
@@ skipping 76 matching lines @@
 
             RefPtrWillBeRawPtr<ConsoleMessage> consoleMessage = ConsoleMessage::create(JSMessageSource, ErrorMessageLevel, embedderErrorMessage, m_resourceName, m_lineNumber, m_columnNumber);
             consoleMessage->setScriptArguments(arguments);
             consoleMessage->setCallStack(m_callStack);
             consoleMessage->setScriptId(m_scriptId);
             m_consoleMessageId = consoleMessage->assignMessageId();
             executionContext->addConsoleMessage(consoleMessage.release());
         }
 
         m_callStack.clear();
+        m_exception.clear();
     }
 
     void revoke()
     {
         ExecutionContext* executionContext = m_scriptState->executionContext();
         if (!executionContext)
             return;
 
         ScriptState::Scope scope(m_scriptState);
         v8::Local<v8::Value> value = m_promise.newLocal(m_scriptState->isolate());
@@ skipping 114 matching lines @@
             continue;
 
         message->report();
         m_reportedAsErrors.append(message.release());
         if (m_reportedAsErrors.size() > maxReportedHandlersPendingResolution)
             m_reportedAsErrors.remove(0, maxReportedHandlersPendingResolution / 10);
     }
 }
 
 } // namespace blink