Update a comment reference from WebKit.h to blink.h

Change-Id: I38f6d8e4756e9da69f733e0b6a356ef9a7cd9082
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1909816Reviewed-by: Kenichi Ishibashi <bashi@chromium.org>
Commit-Queue: Oksana Zhuravlova <oksamyt@chromium.org>
Cr-Commit-Position: refs/heads/master@{#714613}

third_party/blink/renderer/platform/bindings/v8_per_isolate_data.cc

@@ -55,7 +55,7 @@ constexpr char kInterfaceMapLabel[] =
 
 }  // namespace
 
-// Wrapper function defined in WebKit.h
+// Wrapper function defined in blink.h
 v8::Isolate* MainThreadIsolate() {
   return V8PerIsolateData::MainThreadIsolate();
 }