[dart2wasm] Roll binaryen to same version as g3 (~3 months forward)

Change-Id: I3f892ab8493095e8c348b2ed9ee77f8d3f37c958
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/436621
Commit-Queue: Martin Kustermann <[email protected]>
Reviewed-by: Ömer Ağacan <[email protected]>

Author: mkustermann

DEPS

@@ -96,7 +96,7 @@ vars = {
   ### /third_party/ dependencies
 
   # Prefer to use hashes of binaryen that have been reviewed & rolled into g3.
-  "binaryen_rev" : "b4bdcc33115b31758c56b83bb9de4642c411a042",
+  "binaryen_rev" : "8470f1b1f157201d1bc62f3202e474e7043df0ba",
   "boringssl_rev": "035e720641f385e82c72b7b0a9e1d89e58cb5ed5",
   "browser-compat-data_tag": "ac8cae697014da1ff7124fba33b0b4245cc6cd1b", # v1.0.22
   "cpu_features_rev": "936b9ab5515dead115606559502e3864958f7f6e",