Bug 951793 - Export a servo binding to StyleOverscrollBehavior. r=emilio

MozReview-Commit-ID: LlAyLP2IVyp

--HG--
extra : rebase_source : 84ef8ce56d4d4eb4ac07fec37786bf64f88f469e

layout/style/ServoBindings.toml

@@ -173,6 +173,7 @@ rusty-enums = [
     "StyleBoxDecorationBreak",
     "StyleRuleInclusion",
     "StyleGridTrackBreadth",
+    "StyleOverscrollBehavior",
     "nsStyleImageType",
     "StyleWhiteSpace",
     "nsStyleSVGPaintType",