Add iossim testing tool for running iOS unit tests.

testing/iossim/iossim.gyp

+{
+  'variables': {
+    'iphone_sim_path': '$(DEVELOPER_DIR)/Platforms/iPhoneSimulator.platform/Developer/Library/PrivateFrameworks',
+    'other_frameworks_path': '$(DEVELOPER_DIR)/../OtherFrameworks'
+  },
+  'targets': [
+    {
+      'target_name': 'iossim',
+      'type': 'executable',
+      'dependencies': [
+        '<(DEPTH)/testing/iossim/third_party/class-dump/class-dump.gyp:class-dump',
+      ],
+      'include_dirs': [
+        '<(INTERMEDIATE_DIR)/iossim',
+      ],
+      'sources': [
+        'iossim.mm',
+        '<(INTERMEDIATE_DIR)/iossim/iPhoneSimulatorRemoteClient.h',
+      ],
+      'libraries': [
+        '$(SDKROOT)/System/Library/Frameworks/Foundation.framework',
+        '<(iphone_sim_path)/iPhoneSimulatorRemoteClient.framework',
+      ],
+      'mac_framework_dirs': [
+        '<(iphone_sim_path)',
+      ],
+      'xcode_settings': {
+        'LD_RUNPATH_SEARCH_PATHS': '<(iphone_sim_path) <(other_frameworks_path)',
+      },
+      'actions': [
+        {
+          'action_name': 'generate_iphone_sim_header',
+          'inputs': [
+            '<(iphone_sim_path)/iPhoneSimulatorRemoteClient.framework/Versions/Current/iPhoneSimulatorRemoteClient',
+            '$(BUILD_DIR)/$(CONFIGURATION)/class-dump',
+          ],
+          'outputs': [
+            '<(INTERMEDIATE_DIR)/iossim/iPhoneSimulatorRemoteClient.h'
+          ],
+          'action': [
+            # Actions don't provide a way to redirect stdout, so a custom
+            # script is invoked that will execute the first argument and write
+            # the output to the file specified as the second argument.
+            '<(DEPTH)/testing/iossim/RedirectStdout.sh',
+            '$(BUILD_DIR)/$(CONFIGURATION)/class-dump -CiPhoneSimulator <(iphone_sim_path)/iPhoneSimulatorRemoteClient.framework',
+            '<(INTERMEDIATE_DIR)/iossim/iPhoneSimulatorRemoteClient.h',
+          ],
+          'message': 'Generating header',
+        },
+      ],
+    },
+  ],
+}