[fuchsia] Add missing target dependency

The target is missing a dependency and cannot be built in isolation.

Bug: 1127044
Change-Id: I80b53f0d499e999182a2fc4daf6e24dac721b6c4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2404741
Auto-Submit: Fabrice de Gans-Riberi <fdegans@chromium.org>
Commit-Queue: Nate Chapin <japhet@chromium.org>
Reviewed-by: Nate Chapin <japhet@chromium.org>
Cr-Commit-Position: refs/heads/master@{#807306}

third_party/blink/renderer/core/frame/BUILD.gn

@@ -231,6 +231,7 @@ blink_core_sources("frame") {
   }
 
   deps = [
+    "//printing/buildflags",
     "//skia",
     "//ui/accessibility:ax_base",
     "//ui/base/cursor:cursor_base",