Ensure V8 header dependency from translate component

The 'translate' component uses V8 headers (transitively through
blink) without importing the right build config hence getting
potentially wrong definitions due to missing #defines from
the V8 build config.

This CL adds blink_headers as a public dependency to the renderer
target, which fixes the problem for unit_tests and all future
dependents.

Bug: v8:8788
Change-Id: I1d2f3efa19c264a93e1462e916f2305509f0d989
Reviewed-on: https://chromium-review.googlesource.com/c/1454552Reviewed-by: David Roger <droger@chromium.org>
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#629537}

components/translate/content/renderer/BUILD.gn

@@ -22,6 +22,10 @@ static_library("renderer") {
     "//url",
     "//v8",
   ]
+
+  public_deps = [
+    "//third_party/blink/public:blink_headers",
+  ]
 }
 
 source_set("unit_tests") {