DevTools: fix DevTools docs after blink rename

Renames "WebKit/source" to "blink/renderer" references in DevTools.
Skipping presubmit for protocol.json and CodeMirror (usually
requires words "roll CodeMirror" in description when making changes
in cm/ or cm_modes/).

NOPRESUBMIT=true

Bug: none
Change-Id: Iadb44142a5ae1058dae656b93e904c7636f1fa32
Reviewed-on: https://chromium-review.googlesource.com/1003033
Reviewed-by: Dmitry Gozman <[email protected]>
Commit-Queue: Erik Luo <[email protected]>
Cr-Original-Commit-Position: refs/heads/master@{#549220}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: aff59449a34f98ed04cd94547f0ceaaf25d38f71
diff --git a/front_end/externs.js b/front_end/externs.js
index 54fe8f8..df8a357 100644
--- a/front_end/externs.js
+++ b/front_end/externs.js
@@ -28,7 +28,7 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-// WebKit Web Facing API
+// Blink Web Facing API
 
 /**
  * @param {!Object} object