Consider merging https://chromium.googlesource.com/chromium/blink/+/f5c42430625856f4f0a711363fb5b66821314157
Per the specification, if the grid area specified for any <grid-line>
doesn't exist, it should compute to 'auto'. The original parsing
implementation allowed any <grid-line>, which is non-compliant.
This means that "grid-row: foobar / none;" is now (again) rejected
unless the grid element defines the required grid areas.
The testing framework was amended to reuse the existing grid element
so that we get the 'grid-template' definition as we assumed in the
testing. Also added a new test that checks that unknown grid areas
triggers the auto-placement algorithm when appropriate.
This was fixed in bug 120045 which brought grid-area support to WebKit.
*** This bug has been marked as a duplicate of bug 120045 ***