Update from https://crrev.com/309415

Review URL: https://codereview.chromium.org/822713002
diff --git a/third_party/mesa/README.chromium b/third_party/mesa/README.chromium
index 9080655..1a1862f 100644
--- a/third_party/mesa/README.chromium
+++ b/third_party/mesa/README.chromium
@@ -52,3 +52,8 @@
   https://codereview.chromium.org/216773005/
 
 - Excluded src/mapi/mapi/mapi.{h,c} from the build.
+
+- Backported f8e7aa2827e2bdb1ed238cbdd351be3c8a6e9b12 and
+  e20a2df4017ab10dd7199936948c6ac809bfacb6 to fix issues with
+  glGetIntegerv(GL_IMPLEMENTATION_COLOR_READ_FORMAT_OES) when no
+  framebuffer is bound