Make link preview button highlight more opaque for API <20.
Make link preview button highlight more opaque for API <20.

Bug: T116324
Change-Id: I4f93d0c80bdff3eff24a095247361f010039ab3c

wikimedia/apps-android-wikipedia,SAGROUP2/apps-android-wikipedia,carloshwa/apps-android-wikipedia,Duct-and-rice/KrswtkhrWiki4Android,anirudh24seven/apps-android-wikipedia,SAGROUP2/apps-android-wikipedia,SAGROUP2/apps-android-wikipedia,Duct-and-rice/KrswtkhrWiki4Android,wikimedia/apps-android-wikipedia,SAGROUP2/apps-android-wikipedia,Duct-and-rice/KrswtkhrWiki4Android,Duct-and-rice/KrswtkhrWiki4Android,carloshwa/apps-android-wikipedia,dbrant/apps-android-wikipedia,carloshwa/apps-android-wikipedia,Wikinaut/wikipedia-app,anirudh24seven/apps-android-wikipedia,wikimedia/apps-android-wikipedia,dbrant/apps-android-wikipedia,wikimedia/apps-android-wikipedia,carloshwa/apps-android-wikipedia,anirudh24seven/apps-android-wikipedia,dbrant/apps-android-wikipedia,dbrant/apps-android-wikipedia,Wikinaut/wikipedia-app,carloshwa/apps-android-wikipedia,Duct-and-rice/KrswtkhrWiki4Android,Wikinaut/wikipedia-app,Wikinaut/wikipedia-app,SAGROUP2/apps-android-wikipedia,Wikinaut/wikipedia-app,dbrant/apps-android-wikipedia,anirudh24seven/apps-android-wikipedia,anirudh24seven/apps-android-wikipedia