Bug 1338220 - Add webrender dirs to list of third-party code. r=sylvestre

MozReview-Commit-ID: 9QPK6OT3VwX

--HG--
extra : rebase_source : 7fbc104f4aba3604e27cfad57d700b7099e39fd9

tools/rewriting/ThirdPartyPaths.txt

@@ -12,6 +12,8 @@ gfx/harfbuzz/
 gfx/ots/
 gfx/qcms/
 gfx/skia/
+gfx/webrender
+gfx/webrender_traits
 gfx/ycbcr/
 intl/hyphenation/hyphen/
 intl/icu/