Revert "GL: Remove EGL_EXTERNAL_CONTEXT_SAVE_STATE_ANGLE" This reverts commit 4e0250f1926d25e39023c4ad7862ed358a0ec4b6. Reason for revert: Chromium change was reverted. crbug.com/1468956 Original change's description: > GL: Remove EGL_EXTERNAL_CONTEXT_SAVE_STATE_ANGLE > > Now that Chromium no longer uses it. > > Bug: angleproject:5509 > Change-Id: Ibb8d9cdc4d67dad77ca50437423b18d81e838203 > Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/4724768 > Reviewed-by: Peng Huang <penghuang@chromium.org> > Reviewed-by: Geoff Lang <geofflang@chromium.org> > Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org> Bug: angleproject:5509 Change-Id: Id8143b1715ec8162be9351437fbd34a2aa4c2e00 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/4742521 Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>