trivial dart-sdk update to trigger engine rebuild for flutter hotfix (flutter#16344)

pick up a dart-sdk merge commit (no source changed) so that a new build of the engine can be hotfixed into flutter stable v1.12.13.

Author: christopherfujino

DEPS

@@ -34,7 +34,7 @@ vars = {
   # Dart is: https://github.com/dart-lang/sdk/blob/master/DEPS.
   # You can use //tools/dart/create_updated_flutter_deps.py to produce
   # updated revision list of existing dependencies.
-  'dart_revision': 'a4911c63f4f72ba571d6db94de56007b09f4af99',
+  'dart_revision': '4cc36055d6803b899667feaedc1216a96e9d1c72',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py

tools/luci/force_luci_build.sh

@@ -0,0 +1,23 @@
+#!/bin/bash
+
+if [[ -z "$1" ]]; then
+    echo "Usage: $(basename $0) <engine_commit_hash>"
+    exit 1
+fi
+
+ENGINE_COMMIT=$1
+BUILDERS=$(curl 'https://ci.chromium.org/p/flutter/g/engine/builders' 2>/dev/null|sed -En 's:.*aria-label="builder buildbucket/luci\.flutter\.prod/([^/]+)".*:\1:p'|sort|uniq)
+
+# This property is only for hotfixes to branches prior to this feature being added
+# See https://github.com/flutter/engine/commit/abaac56c602cad3c1b3e41633bbfbe65200a1a3a
+NO_FONT_SUBSET="-p build_font_subset=false"
+
+IFS=$'\n'
+for BUILDER in $BUILDERS; do
+    echo "Building $BUILDER..."
+    bb add \
+       -commit "https://chromium.googlesource.com/external/github.com/flutter/engine/+/$ENGINE_COMMIT" \
+       "flutter/prod/$BUILDER" \
+       $NO_FONT_SUBSET
+    sleep 1
+done