Revert 167728 "Avoid calling Node::numberOfScopedHTMLStyleChildr..."

fast/css/style-scoped/changing-scoped-attribute-asan-crash.html started to crash after r167728.

> Avoid calling Node::numberOfScopedHTMLStyleChildren() to check for existence
> 
> Avoid calling Node::numberOfScopedHTMLStyleChildren() to check for existence as
> we don't want to traverse all children merely to check for the existence
> of 1 child. Node::hasScopedHTMLStyleChild() can be used to check this instead
> as we have a dedicated flag for this. Also, don't unnecessarily traverse all
> children to set the HasScopedHTMLStyleChildFlag, and break early instead as
> soon as one child is found.
> 
> R=adamk, eseidel
> 
> Review URL: https://codereview.chromium.org/178333005

TBR=ch.dumez@samsung.com

Review URL: https://codereview.chromium.org/179693003

git-svn-id: svn://svn.chromium.org/blink/trunk@167771 bbb929c8-8fbe-4397-9dbb-9b2b20218538