- Modify dart_api.h to be a proper C API.

runtime/bin/bin.gypi

 # Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
 {
   'variables': {
     # We place most generated source files in LIB_DIR (rather than, say
     # SHARED_INTERMEDIATE_DIR) because it is toolset specific. This avoids
     # two problems. First, if a generated source file has architecture specific
     # code, we'll get two different files in two different directories. Second,
@@ skipping 638 matching lines @@
         {
           'target_name': 'test_extension',
           'type': 'shared_library',
           'dependencies': [
             'dart',
           ],
           'include_dirs': [
             '..',
           ],
           'sources': [
-            'test_extension.cc',
+            'test_extension.c',
             'test_extension_dllmain_win.cc',
           ],
           'defines': [
             # The only effect of DART_SHARED_LIB is to export the Dart API.
             'DART_SHARED_LIB',
           ],
           'conditions': [
             ['OS=="win"', {
               'msvs_settings': {
                 'VCLinkerTool': {
@@ skipping 12 matching lines @@
                 '-fPIC',
               ],
             }],
           ],
         },
       ],
     }],
   ],
 }