Roll ANGLE 524e3bde19..6bd5831261

https://chromium.googlesource.com/angle/angle/+log/524e3bde19..6bd5831261

BUG=466735,466704

Review URL: https://codereview.chromium.org/1011213002

Cr-Commit-Position: refs/heads/master@{#320988}

DEPS

@@ -58,7 +58,7 @@ vars = {
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling ANGLE
   # and whatever else without interference from each other.
-  'angle_revision': '524e3bde19d0df76cc9d1c5926345f5d0ec4d3f8',
+  'angle_revision': '6bd5831261ff96fb7abf224a9a7ead5e2c97fdc9',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling build tools
   # and whatever else without interference from each other.