Revert 162740 "Optimization in handleStyleSpans() for restrictin..."

I'm not sure why r162740 causes heap-use-after-free. The patch changes
to end of loop node before loop rather than every iteration. I would
like to see reverting r162740 fixes heap-use-after-free.

> Optimization in handleStyleSpans() for restricting the for loop to iterate only
> over the InsertedNodes (i.e. the inserted fragment).
> This is in line with other methods such as removeRedundantStylesAndKeepStyleSpanInline()
> and makeInsertedContentRoundTrippableWithHTMLTreeBuilder() that iterate over
> the InsertedNodes.
> 
> No existing test should fail with this patch.
> 
> Review URL: https://codereview.chromium.org/72743002

TBR=a.bah@samsung.com
BUG=324324

Review URL: https://codereview.chromium.org/98063003

git-svn-id: svn://svn.chromium.org/blink/trunk@162957 bbb929c8-8fbe-4397-9dbb-9b2b20218538