Add check for iOS simulator when initializing caps in metal On Intel-arch MacBook, the system API [supportsFamily:MTLGPUFamilyApple3] returns false on the iOS simulator, causing maxVertexOutputComponents to be set to 60, which is below than the required value of 64, resulting in WebGL2 initialization failure on chromium iOS. Add a TARGET_OS_SIMULATOR check to ensure the values of caps can be set correctly in the siumulator environment. Bug: angleproject:375244081 Change-Id: Iafc44a2aa62130b09127bbec7ea6940506a4165c Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/5961039 Reviewed-by: Kimmo Kinnunen <kkinnunen@apple.com> Reviewed-by: Corentin Wallez <cwallez@chromium.org> Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>