Oilpan: Change Persistent<> data members to Member<> in HitTestResult.

Source/web/mac/WebSubstringUtil.mm

Index: Source/web/mac/WebSubstringUtil.mm
diff --git a/Source/web/mac/WebSubstringUtil.mm b/Source/web/mac/WebSubstringUtil.mm
index d14d4fd2ac8a79ed925f67b8e14baccbcd6c5342..8df070c5393eb44efa0ce506d90ce4b845be7ba4 100644
--- a/Source/web/mac/WebSubstringUtil.mm
+++ b/Source/web/mac/WebSubstringUtil.mm
@@ -55,6 +55,7 @@
 #include "public/web/WebRange.h"
 #include "public/web/WebView.h"
 #include "web/WebLocalFrameImpl.h"
+#include "web/WebViewImpl.h"
 
 using namespace WebCore;
 
@@ -112,7 +113,7 @@ namespace blink {
 
 NSAttributedString* WebSubstringUtil::attributedWordAtPoint(WebView* view, WebPoint point, WebPoint& baselinePoint)
 {
-    HitTestResult result = view->hitTestResultAt(point);
+    HitTestResult result = static_cast<WebViewImpl*>(view)->coreHitTestResultAt(point);
     if (!result.targetNode())
       return nil;
     LocalFrame* frame = result.targetNode()->document().frame();