Convert SecurityError exceptions to 'es.throwSecurityError()'.

Source/core/page/EventSource.cpp

Index: Source/core/page/EventSource.cpp
diff --git a/Source/core/page/EventSource.cpp b/Source/core/page/EventSource.cpp
index 24b96083fdcd3c3ba0f8f741c885e94bfd92e074..f9cb1c52ec508fb95249d1d077e7f15ab24e9fab 100644
--- a/Source/core/page/EventSource.cpp
+++ b/Source/core/page/EventSource.cpp
@@ -92,7 +92,8 @@ PassRefPtr<EventSource> EventSource::create(ScriptExecutionContext* context, con
         shouldBypassMainWorldContentSecurityPolicy = document->frame()->script()->shouldBypassMainWorldContentSecurityPolicy();
     }
     if (!shouldBypassMainWorldContentSecurityPolicy && !context->contentSecurityPolicy()->allowConnectToSource(fullURL)) {
-        es.throwDOMException(SecurityError, "Refused to connect to '" + fullURL.elidedString() + "' because it violates the document's Content Security Policy.");
+        // We can safely expose the URL to JavaScript, as this exception is generate synchronously before any redirects take place.
+        es.throwSecurityError("Refused to connect to '" + fullURL.elidedString() + "' because it violates the document's Content Security Policy.");
         return 0;
     }