Bug 1514019 - Update webrender to commit e9ea9d894b2a1c99dabd117ecd0597df796f8c84 (WR PR #3411). r=kats

https://github.com/servo/webrender/pull/3411

Differential Revision: https://phabricator.services.mozilla.com/D14534

--HG--
extra : moz-landing-system : lando

gfx/webrender_bindings/revision.txt

@@ -1 +1 @@
-d983969265589de30dc69b755ca8b3db66bff435
+e9ea9d894b2a1c99dabd117ecd0597df796f8c84

gfx/wr/webrender/res/brush_blend.glsl

@@ -150,7 +150,7 @@ Fragment brush_fs() {
 
     // Un-premultiply the input.
     float alpha = Cs.a;
-    vec3 color = Cs.rgb / Cs.a;
+    vec3 color = alpha != 0.0 ? Cs.rgb / alpha : Cs.rgb;
 
     switch (vOp) {
         case 0: