DevTools: fix typo in protocol description

R=dgozman@chromium.org

Fixed: 1062535
Change-Id: I5a64b6e0d6be71470a34a007c674dc44347f11fd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2119859Reviewed-by: Andrey Kosyakov <caseq@chromium.org>
Commit-Queue: Andrey Kosyakov <caseq@chromium.org>
Cr-Commit-Position: refs/heads/master@{#753284}

third_party/blink/public/devtools_protocol/browser_protocol.pdl

@@ -7259,7 +7259,7 @@ experimental domain Fetch
       optional string method
       # If set, overrides the post data in the request.
       optional string postData
-      # If set, overrides the request headrts.
+      # If set, overrides the request headers.
       optional array of HeaderEntry headers
 
   # Continues a request supplying authChallengeResponse following authRequired event.