Revert "android: disable deobfuscation in tests."

This reverts commit b81f63ce.

Reason for revert: retrace bug now fixed

Original change's description:
> android: disable deobfuscation in tests.
>
> Deobfuscation appears to be hanging in ways that cause it to peg
> bots' CPUs and kill test runs. This CL temporarily disables it as
> a mitigation.
>
> Bug: 876539
> Change-Id: I6dced1a4c80e630bb701a17eaa8322450661adc5
> Reviewed-on: https://chromium-review.googlesource.com/1185294
> Reviewed-by: Ben Pastene <bpastene@chromium.org>
> Commit-Queue: John Budorick <jbudorick@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#585190}

Bug: 876539
Change-Id: If6c19b7345e769d51d1580980aca8e3967319a97
Reviewed-on: https://chromium-review.googlesource.com/1195432Reviewed-by: Ben Pastene <bpastene@chromium.org>
Reviewed-by: agrieve <agrieve@chromium.org>
Commit-Queue: agrieve <agrieve@chromium.org>
Cr-Commit-Position: refs/heads/master@{#587707}

build/config/android/internal_rules.gni

@@ -603,10 +603,7 @@ template("test_runner_script") {
         }
         test_runner_args += [ "--apk-under-test=$_apk_under_test" ]
       }
-      if (defined(invoker.proguard_enabled) && invoker.proguard_enabled &&
-          # TODO(crbug.com/876539): Reenable deobfuscation once it stops killing
-          # bots.
-          false) {
+      if (defined(invoker.proguard_enabled) && invoker.proguard_enabled) {
         test_runner_args += [ "--enable-java-deobfuscation" ]
       }
       if (emma_coverage) {