[webkit-reviews] review requested: [Bug 74135] [CSS Regions] Auto width is not working for Regions : [Attachment 162528] Patch 4

[bugzilla-daemon at webkit.org]

Mihnea Ovidenie <mihnea at adobe.com> has asked  for review:
Bug 74135: [CSS Regions] Auto width is not working for Regions
https://bugs.webkit.org/show_bug.cgi?id=74135

Attachment 162528: Patch 4
https://bugs.webkit.org/attachment.cgi?id=162528&action=review

------- Additional Comments from Mihnea Ovidenie <mihnea at adobe.com>
The crash (stack overflow) was seen in the following situation:
* a region with width:auto is attached to a flow thread
* because there are some circular dependencies between the regions and the flow
threads in the page, the region above is not valid, meaning that it should not
receive content from the associated flow thread
* the region has the characteristics of using the shrink-to-fit algorithm for
computing the width

In this situation, when computing the width of the region, the code used the
min/maxPreferredWidth from flowThread, which, because of circular dependencies,
caused the repeated call of minPreferredLogicalWidth, thus causing the stack
overflow.

The fix is to test the validity of the region (besides being attached to a flow
thread) before attempting to use the min/maxPreferredWidth from the flowThread.