https://trac.webkit.org/changeset/263960 broke the build:
Re-land, because r263959 somehow fixed the build issue caused by r263953
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Created attachment 403568 [details]
REVERT of r263960
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webkit-patch land-attachment ATTACHMENT_ID
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Committed r263961: <https://trac.webkit.org/changeset/263961>
All reviewed patches have been landed. Closing bug and clearing flags on attachment 403568 [details].
OK, some notes for the record on what I figured out after the fact.
The reason that r263953 broke Apple's internal builds is that there was a bug in the DerivedSources.make files where FEATURE_DEFINE_FLAGS would incorrect be defined as "-D" if FEATURE_DEFINES was empty. The reason that FEATURE_DEFINES was empty on the internal builds after r263953 is that the only feature left there was ENABLE_EXPERIMENTAL_FEATURES. That was enabled for builds on individual engineer’s computers, and the open source builds, but not for Apple internal production builds.
The reason that r263959 made the problem go away is that it deleted FEATURE_DEFINE_FLAGS entirely, taking the bug with it.