Replace GetSymbol using void* with new GetSymbol using SymbolKey in GetHistoryStateSymbol

This CL replaces the old GetSymbol, which uses void* as a key, with the new GetSymbol, which uses an instance of SymbolKey created in CL1877490 as a key, in GetHistoryStateSymbol.

Bug: 715418
Change-Id: Iab40205b1793c42ef8cedf82ee9f9ea2ee46c337
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1877501
Commit-Queue: Marina Sakai <marinasakai@google.com>
Reviewed-by: Yuki Shiino <yukishiino@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Hitoshi Yoshida <peria@chromium.org>
Cr-Commit-Position: refs/heads/master@{#709341}

third_party/blink/renderer/platform/bindings/v8_private_property.h

@@ -207,8 +207,8 @@ class PLATFORM_EXPORT V8PrivateProperty {
   // This is a hack for PopStateEvent to get the same private property of
   // History, named State.
   static Symbol GetHistoryStateSymbol(v8::Isolate* isolate) {
-    static int private_property_key;
-    return GetSymbol(isolate, &private_property_key, "History#State");
+    static const SymbolKey private_property_key("History#State");
+    return GetSymbol(isolate, private_property_key);
   }
 
   // Returns a Symbol to access a private property. Symbol instances from same