Make browsing context keywords case-insensitive.

third_party/WebKit/Source/core/frame/LocalDOMWindow.cpp

Index: third_party/WebKit/Source/core/frame/LocalDOMWindow.cpp
diff --git a/third_party/WebKit/Source/core/frame/LocalDOMWindow.cpp b/third_party/WebKit/Source/core/frame/LocalDOMWindow.cpp
index cae0bb12134adec74ada3184674c5fb56990de92..f4bfc6288897a62ce5508634a8f77f8974636b47 100644
--- a/third_party/WebKit/Source/core/frame/LocalDOMWindow.cpp
+++ b/third_party/WebKit/Source/core/frame/LocalDOMWindow.cpp
@@ -1587,9 +1587,9 @@ DOMWindow* LocalDOMWindow::open(const String& urlString,
   // Get the target frame for the special cases of _top and _parent.
   // In those cases, we schedule a location change right now and return early.
   Frame* targetFrame = nullptr;
-  if (frameName == "_top") {
+  if (equalIgnoringASCIICase(frameName, "_top")) {
     targetFrame = frame()->tree().top();
-  } else if (frameName == "_parent") {
+  } else if (equalIgnoringASCIICase(frameName, "_parent")) {
     if (Frame* parent = frame()->tree().parent())
       targetFrame = parent;
     else