Build //ios:all and its dependencies on the iOS builders.

ios/build/bots/chromium.mac/ios-device.json

 {
   "owners": [
     "dpranke",
     "smut"
   ],
   "comments": [
     "Builder for 32-bit devices.",
     "Build is performed with gn+ninja."
   ],
   "xcode version": "8.0",
   "gn_args": [
     "additional_target_cpus=[ \"arm64\" ]",
     "goma_dir=\"$(goma_dir)\"",
     "ios_enable_code_signing=false",
     "is_component_build=false",
     "is_debug=true",
     "target_cpu=\"arm\"",
     "target_os=\"ios\"",
     "use_goma=true"
   ],
+  "additional_compile_targets": [
+    "ios:all"
+  ],
   "compiler": "ninja",
   "configuration": "Release",
   "sdk": "iphoneos10.0",
   "tests": [
   ]
 }