Add prerequisite dependencies to make ios_test work build on bazel.

--
MOS_MIGRATED_REVID=104673050
diff --git a/tools/objc/BUILD b/tools/objc/BUILD
index 7f87137..1e2875c 100644
--- a/tools/objc/BUILD
+++ b/tools/objc/BUILD
@@ -47,11 +47,12 @@
 
 filegroup(
     name = "srcs",
-    srcs = glob(["**"]),
+    srcs = glob(["**"]) + ["//tools/objc/sim_devices:BUILD"],
 )
 
 filegroup(
     name = "testrunner",
+    srcs = [":testrunner_stub"],
 )
 
 sh_binary(
diff --git a/tools/objc/sim_devices/BUILD b/tools/objc/sim_devices/BUILD
new file mode 100644
index 0000000..5d81e1b
--- /dev/null
+++ b/tools/objc/sim_devices/BUILD
@@ -0,0 +1,7 @@
+package(default_visibility = ["//visibility:public"])
+
+ios_device(
+    name = "default",
+    ios_version = "8.4",
+    type = "IPHONE",
+)
diff --git a/tools/objc/testrunner_stub b/tools/objc/testrunner_stub
new file mode 100644
index 0000000..5c7a546
--- /dev/null
+++ b/tools/objc/testrunner_stub
@@ -0,0 +1,8 @@
+#!/bin/bash
+
+(
+  printf 'Bazel does not support running ios_tests directly.\n'
+  printf 'Use "bazel build (TARGET) to generate an .xcodeproj."\n'
+) >&2
+
+exit 1