Remove -internals-media-controls-cast-button as web exposed CSS selector.

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

Index: third_party/WebKit/Source/core/frame/Deprecation.cpp
diff --git a/third_party/WebKit/Source/core/frame/Deprecation.cpp b/third_party/WebKit/Source/core/frame/Deprecation.cpp
index e8ab30e7254d6fb9d7fa987897f9d47249673923..dfaefb26b637a251329be476391ed28e81af853a 100644
--- a/third_party/WebKit/Source/core/frame/Deprecation.cpp
+++ b/third_party/WebKit/Source/core/frame/Deprecation.cpp
@@ -389,10 +389,6 @@ String Deprecation::deprecationMessage(UseCounter::Feature feature) {
           "redirected response. This will result in an error in %s.",
           milestoneString(M59));
 
-    case UseCounter::CSSSelectorInternalMediaControlsCastButton:
-      return willBeRemoved("-internal-media-controls-cast-button selector", M59,
-                           "5734009183141888");
-
     case UseCounter::CSSSelectorInternalMediaControlsOverlayCastButton:
       return willBeRemoved(
           "-internal-media-controls-overlay-cast-button selector", M59,