DevTools: [Sources] Improve editor load time by optimizing setMimeType

third_party/WebKit/LayoutTests/inspector/editor/php-highlighter.html

Index: third_party/WebKit/LayoutTests/inspector/editor/php-highlighter.html
diff --git a/third_party/WebKit/LayoutTests/inspector/editor/php-highlighter.html b/third_party/WebKit/LayoutTests/inspector/editor/php-highlighter.html
index 57e54a6ac586217afd676ec00d1265c443514f49..c70bcc28cf074b321b76b0f4286f8f845705c9c3 100644
--- a/third_party/WebKit/LayoutTests/inspector/editor/php-highlighter.html
+++ b/third_party/WebKit/LayoutTests/inspector/editor/php-highlighter.html
@@ -7,8 +7,8 @@ function test()
 {
     var mimeType = "text/x-php";
     var textEditor = InspectorTest.createTestEditor();
-    textEditor.setMimeType(mimeType).then(onModesLoaded);
-
+    InspectorTest.addSnifferPromise(SourceFrame.SourcesTextEditor.prototype, "rewriteMimeType").then(onModesLoaded);
+    textEditor.setMimeType(mimeType);
     function onModesLoaded()
     {
         InspectorTest.addResult("Mode loaded: " + !!CodeMirror.mimeModes[mimeType]);