Add a test to obtain offsetWidth of expanded table cell
Created attachment 216104 [details] Adds a test
Merging the test from https://chromium.googlesource.com/chromium/blink/+/58a5fac292a5b3f79b00cdc71074fbf8be2ebc2b This will ensure that we'll not introduce the regression Blink had when we optimize offsetWidth.
Committed r158710: <http://trac.webkit.org/changeset/158710>
Committed r158711: <http://trac.webkit.org/changeset/158711>