Skip `fast/writing-mode/text-combine-line-break.html` on Mac.

`fast/writing-mode/text-combine-line-break.html` began failing on Mac bots somewhere in the range https://chromium.googlesource.com/chromium/src/+log/643cb72034fb069695bda8dfb3e8f1af35069923%5E..a9d08087510ec8ce3f6f098a64aed29d93f9ee2d?pretty=fuller&n=

*  http://build.chromium.org/p/chromium.mac/builders/Mac10.10%20Tests/builds/43396
*  http://build.chromium.org/p/chromium.mac/builders/WebKit%20Mac10.13%20(retina)/builds/14811
*  http://build.chromium.org/p/chromium.mac/builders/Mac10.13%20Tests/builds/13959
*  http://build.chromium.org/p/chromium.mac/builders/Mac10.12%20Tests/builds/23420
*  http://build.chromium.org/p/chromium.mac/builders/Mac10.11%20Tests/builds/38409

Given the nature of the failure (`0` => `-0`), I suspect  https://chromium-review.googlesource.com/c/chromium/src/+/1614448, but it doesn't cleanly revert.

Updating text expectations, and assigning to  wangxianzhu@chromium.org for investigation.

TBR=wangxianzhu@chromium.org

Change-Id: Ic37fc83ee6feaaf558ec9bd5e3b3010323c17948
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 968033
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1634849
Commit-Queue: Mike West <mkwst@chromium.org>
Reviewed-by: Mike West <mkwst@chromium.org>
Cr-Commit-Position: refs/heads/master@{#664166}

third_party/blink/web_tests/TestExpectations

@@ -2118,6 +2118,8 @@ crbug.com/658305 css3/filters/effect-reference-zoom.html [ Failure Pass ]
 crbug.com/658305 css3/filters/effect-reference-zoom-hw.html [ Failure Pass ]
 crbug.com/658305 css3/filters/filter-effect-removed.html [ Failure Pass ]
 
+crbug.com/968033 [ Mac ] fast/writing-mode/text-combine-line-break.html [ Failure ]
+
 crbug.com/524160 [ Debug ] http/tests/media/media-source/stream_memory_tests/mediasource-appendbuffer-quota-exceeded-default-buffers.html [ Timeout ]
 
 # Run the tests with the default MSE buffer sizes in the main test suite and the tests for 1MB buffers set via command line in a virtual test suite