[CSSRegions][CSSOM]Restrict parsing of named flow name

[CSSRegions][CSSOM]Restrict parsing of named flow name
https://bugs.webkit.org/show_bug.cgi?id=80359

Reviewed by Andreas Kling.

The function that does the parsing for flow thread name should restrict the
number of parsed properties to 1, otherwise it would allow parsing of
"-webkit-flow-into: flow; color: red;" constructions.

Source/WebCore:

Modified fast/regions/webkit-named-flow-invalid-name.html to include the above case.

* css/CSSParser.cpp:
(WebCore::validFlowName):
(WebCore::CSSParser::parseFlowThread):

LayoutTests:

* fast/regions/webkit-named-flow-invalid-name-expected.txt:
* fast/regions/webkit-named-flow-invalid-name.html:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@109961 268f45cc-cd09-0410-ab3c-d52691b4dbfc