Bug 1134585, remove cpow usage from view selection source, r=mconley

browser/base/content/nsContextMenu.js

testing/mochitest/BrowserTestUtils/BrowserTestUtils.jsm

toolkit/components/viewsource/ViewSourceBrowser.jsm

toolkit/components/viewsource/content/viewPartialSource.js

toolkit/components/viewsource/content/viewSource-content.js

toolkit/components/viewsource/content/viewSource.js

toolkit/components/viewsource/content/viewSourceUtils.js

toolkit/components/viewsource/test/browser/browser.ini

...t/components/viewsource/test/browser/browser_bug464222.js

...t/components/viewsource/test/browser/browser_bug713810.js

...components/viewsource/test/browser/browser_contextmenu.js

toolkit/components/viewsource/test/browser/head.js

toolkit/content/browser-content.js