Fix IsMacOSVersionAtLeast for IOS platform build

Change-Id: Ia8caf2459049b80855922059a4baf92268f8d83a
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/134701
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Loko Kung <lokokung@google.com>
Commit-Queue: Shrek Shao <shrekshao@google.com>
Reviewed-by: Austin Eng <enga@chromium.org>
diff --git a/src/dawn/native/metal/BackendMTL.mm b/src/dawn/native/metal/BackendMTL.mm
index 79f70ee..9a5d78e 100644
--- a/src/dawn/native/metal/BackendMTL.mm
+++ b/src/dawn/native/metal/BackendMTL.mm
@@ -486,9 +486,11 @@
                 if (gpu_info::IsIntelGen11(vendorId, deviceId)) {
                     return true;
                 }
+#if DAWN_PLATFORM_IS(MACOS)
                 if (gpu_info::IsIntel(vendorId) && !IsMacOSVersionAtLeast(11)) {
                     return true;
                 }
+#endif
                 return false;
             };
             if (ShouldLeakCounterSets()) {