Remove webkit dependency in grit_rule.

build/secondary/tools/grit/grit_rule.gni

Index: build/secondary/tools/grit/grit_rule.gni
diff --git a/build/secondary/tools/grit/grit_rule.gni b/build/secondary/tools/grit/grit_rule.gni
index 13bb8e0ec9c59dbd98e28be52de925376b4f2885..260cf8d8d1be6f7050c6787e244eaba7d614ee0d 100644
--- a/build/secondary/tools/grit/grit_rule.gni
+++ b/build/secondary/tools/grit/grit_rule.gni
@@ -79,7 +79,6 @@
 #     # files.
 #   }
 import("//build/config/chrome_build.gni")
-import("//third_party/WebKit/Source/config.gni")
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
@@ -251,13 +250,6 @@ if (enable_google_now) {
   ]
 }
 
-if (use_concatenated_impulse_responses) {
-  grit_defines += [
-    "-D",
-    "use_concatenated_impulse_responses",
-  ]
-}
-
 if (enable_webrtc) {
   grit_defines += [
     "-D",