Remove use_allocator=none where it's implied.

scripts/slave/recipes/chromium.expected/full_chromium_fyi_ClangToTAndroidASan.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "[BUILD]/scripts/slave/bot_update.py",
       "--master",
       "chromium.fyi",
       "--builder",
       "ClangToTAndroidASan",
@@ skipping 51 matching lines @@
   },
   {
     "cmd": [
       "python",
       "-u",
       "[DEPOT_TOOLS]/gclient.py",
       "runhooks"
     ],
     "env": {
       "GYP_CROSSCOMPILE": "1",
-      "GYP_DEFINES": "OS=android asan=1 clang=1 clang_use_chrome_plugins=0 component=shared_library fastbuild=1 lsan=1 target_arch=arm use_allocator=none werror=''",
+      "GYP_DEFINES": "OS=android asan=1 clang=1 clang_use_chrome_plugins=0 component=shared_library fastbuild=1 lsan=1 target_arch=arm werror=''",
       "LLVM_FORCE_HEAD_REVISION": "YES",
       "PATH": "[SLAVE_BUILD]/src/third_party/android_tools/sdk/platform-tools:[SLAVE_BUILD]/src/build/android:%(PATH)s"
     },
     "name": "gclient runhooks"
   },
   {
     "cmd": [
       "python",
       "-u",
       "\nimport shutil\nimport sys\nshutil.copy(sys.argv[1], sys.argv[2])\n",
@@ skipping 70 matching lines @@
       "--build_revision",
       "f27fede2220bcd326aee3e86ddfd4ebd0fe58cb9",
       "--factory-properties",
       "{\"blamelist\": [\"cool_dev1337@chromium.org\", \"hax@chromium.org\"], \"buildername\": \"ClangToTAndroidASan\", \"buildnumber\": 571, \"mastername\": \"chromium.fyi\", \"parent_buildername\": null, \"recipe\": \"chromium\", \"slavename\": \"TestSlavename\", \"workdir\": \"/path/to/workdir/TestSlavename\"}",
       "--build-properties",
       "{\"blamelist\": [\"cool_dev1337@chromium.org\", \"hax@chromium.org\"], \"buildername\": \"ClangToTAndroidASan\", \"buildnumber\": 571, \"mastername\": \"chromium.fyi\", \"parent_buildername\": null, \"recipe\": \"chromium\", \"slavename\": \"TestSlavename\", \"workdir\": \"/path/to/workdir/TestSlavename\"}"
     ],
     "name": "package build"
   }
 ]