Add protocolIsInHTTPFamily for strings and use it where appropriate

https://bugs.webkit.org/show_bug.cgi?id=127336

Reviewed by Alexey Proskuryakov.

* html/HTMLAnchorElement.cpp:
(WebCore::HTMLAnchorElement::parseAttribute):
* page/ContentSecurityPolicy.cpp:
(WebCore::CSPSource::schemeMatches):
* page/SecurityPolicy.cpp:
(WebCore::SecurityPolicy::generateReferrerHeader):
* platform/URL.cpp:
(WebCore::protocolIsInHTTPFamily):
* platform/URL.h:


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@162555 268f45cc-cd09-0410-ab3c-d52691b4dbfc