The ES2015 specification requires that String.prototype.startsWith,
String.prototype.endsWith and String.prototype.includes use the IsRegExp
internal algorithm to determine whether to throw a TypeError to prevent
a RegExp from being accidentally cast to a String for those methods.
That internal algorithm checks the presence/truthiness of Symbol.match
to make its determination. This patch switches the builtins to use
this correct test, rather than checking for the [[RegExpMatcher]]
internal slot as the builtins previously did.

R=yangguo

Review URL: https://codereview.chromium.org/1762183002

Cr-Commit-Position: refs/heads/master@{#34547}