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

ios/build/bots/chromium.fyi/ios-simulator.json

 {
   "owners": [
     "smut"
   ],
   "comments": [
     "Runs tests on @3x, @2x, 64-bit, 32-bit, phone, tablet, iOS 10, and iOS 9."
   ],
   "xcode version": "8.0",
   "gn_args": [
     "additional_target_cpus=[\"x86\"]",
     "goma_dir=\"$(goma_dir)\"",
     "ios_enable_code_signing=false",
     "is_component_build=false",
     "is_debug=true",
     "target_cpu=\"x64\"",
     "target_os=\"ios\"",
     "use_goma=true"
   ],
+  "additional_compile_targets": [
+    "ios:all"
+  ],
   "compiler": "ninja",
   "configuration": "Debug",
   "sdk": "iphonesimulator10.0",
   "tests": [
     {
       "include": "common_tests.json",
       "device type": "iPhone 6s Plus",
       "os": "10.0"
     },
     {
@@ skipping 36 matching lines @@
       "device type": "iPad Air 2",
       "os": "9.0"
     },
     {
       "include": "common_tests.json",
       "device type": "iPad Retina",
       "os": "9.0"
     }
   ]
 }