Add GN build rules to allow java_assertion_enabler to enable Java asserts.

BUILD.gn

Index: BUILD.gn
diff --git a/BUILD.gn b/BUILD.gn
index 64ab23176ef3667103ebf2722b52ae8bbf930c47..e3b88d189cd01cbcc44cdc74a2bb2fb860909bd3 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -852,11 +852,7 @@ group("gn_only") {
   }
 
   if (is_android) {
-    deps += [
-      "//build/android/gyp/test:hello_world",
-      "//build/android/incremental_install:bootstrap_java",

[agrieve, 2016/11/14 19:00:57]

note: I said this was fine to remove as well since it's also referenced by
targets (in a similar way to java_assertion_enabler)

-      "//build/android/java_assertion_enabler",
-    ]
+    deps += [ "//build/android/gyp/test:hello_world" ]
   }
 
   if (is_linux && use_ozone) {