Remove obsolete SkFontHost_mac.cpp entry in skia/BUILD.gn.

SkFontHost_mac.cpp no longer exists in Skia, but still have an iOS-only
reference in skia/BUILD.gn. Delete it.

Change-Id: If0b5d216adcf2b2d9c16277f91212aed7560051c
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/71151
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: Ben Wagner <bungeman@google.com>
diff --git a/skia/BUILD.gn b/skia/BUILD.gn
index c8d4496..066108d 100644
--- a/skia/BUILD.gn
+++ b/skia/BUILD.gn
@@ -329,10 +329,7 @@
   if (is_ios) {
     libs = [ "ImageIO.framework" ]
     set_sources_assignment_filter([])
-    sources += [
-      "//third_party/skia/src/ports/SkFontHost_mac.cpp",
-      "//third_party/skia/src/utils/mac/SkCreateCGImageRef.cpp",
-    ]
+    sources += [ "//third_party/skia/src/utils/mac/SkCreateCGImageRef.cpp" ]
     set_sources_assignment_filter(sources_assignment_filter)
   }