Do not attempt to remove SkFrontBufferedStream

Bug: skia:10154

This file is being moved in
https://skia-review.googlesource.com/c/skia/+/284721. Once that CL
lands in upstream Skia, there will be no need to remove it, since Skia's
build files will not tell the build system to build it.

Change-Id: Ib886325168042f7fe6ce279182462b0200f1ae11
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2158929
Auto-Submit: Leon Scroggins <scroggo@google.com>
Commit-Queue: Mike Reed <reed@google.com>
Reviewed-by: Mike Reed <reed@google.com>
Cr-Commit-Position: refs/heads/master@{#761107}

skia/BUILD.gn

@@ -382,7 +382,6 @@ component("skia") {
 
   # Remove unused util sources.
   sources -= [
-    "//third_party/skia/src/utils/SkFrontBufferedStream.cpp",
     "//third_party/skia/src/utils/SkInterpolator.cpp",
     "//third_party/skia/src/utils/SkParsePath.cpp",
   ]