Rolling R8 from 3.1.2 -> 3.1.8

Bug: 1168577
Change-Id: I367d64dc6946e575aafac47b85e3dbfda99186f7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2963912
Auto-Submit: Sam Maier <smaier@chromium.org>
Commit-Queue: Andrew Grieve <agrieve@chromium.org>
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Cr-Commit-Position: refs/heads/master@{#892683}
diff --git a/DEPS b/DEPS
index 2b06443..52243b18 100644
--- a/DEPS
+++ b/DEPS
@@ -1469,7 +1469,7 @@
       'packages': [
           {
               'package': 'chromium/third_party/r8',
-              'version': 'gXyBDv_fM87KnLcxvF5AGV5lwnm-JXIALYH8zrzdoaMC',
+              'version': 'o1uegxayAMktc600LZ1gX5ZzkC_qhU-frNcWJfmBg98C',
           },
       ],
       'condition': 'checkout_android',
diff --git a/third_party/r8/README.chromium b/third_party/r8/README.chromium
index b84107c..a4bd90f 100644
--- a/third_party/r8/README.chromium
+++ b/third_party/r8/README.chromium
@@ -1,6 +1,6 @@
 Name: R8
 URL: https://r8.googlesource.com/r8
-Version: 3.1.2-dev
+Version: 3.1.8
 License: BSD 3-Clause
 License File: NOT_SHIPPED
 Security Critical: no