Fix tab crashes on inspecting view-source:... pages

The problem was that SPAN element was created by calling HTMLElement::create instead of HTMLSpanElement::create which resulted in webCoreInitializeScriptWrappableForInterface(WebCore::HTMLElement*) being called instead of webCoreInitializeScriptWrappableForInterface(WebCore::HTMLSpanElement*) to initilize typeInfo field in the object.

BUG=312567

Review URL: https://codereview.chromium.org/55903002

git-svn-id: svn://svn.chromium.org/blink/trunk@161170 bbb929c8-8fbe-4397-9dbb-9b2b20218538