ASSERTION FAILED: !extraRowSpanningHeight in WebCore::RenderTableSection::distributeRowSpanHeightToRows

Spanning rows have only percent rows and total percent is less than 100 So only
percent portion of extraRowSpnnaingHeight is consumed in percent spanning rows and
remaining is left to distribute in non-spanning rows. But non-percent rows height
is zero So assertion is failing.

Now, whole extraRowSpanningHeight is distributed to percent spanning rows if non-percent
spanning rows height is zero.

R=jchaffraix@chromium.org
BUG=366579

Review URL: https://codereview.chromium.org/398013005

git-svn-id: svn://svn.chromium.org/blink/trunk@180417 bbb929c8-8fbe-4397-9dbb-9b2b20218538