Import Dart bindings as of Blink r188698. This merely copies the files over and does not attach any…

sky/engine/bindings-dart/core/dart/DartPersistentValue.cpp

Index: sky/engine/bindings-dart/core/dart/DartPersistentValue.cpp
diff --git a/sky/engine/platform/exported/Platform.cpp b/sky/engine/bindings-dart/core/dart/DartPersistentValue.cpp
similarity index 74%
copy from sky/engine/platform/exported/Platform.cpp
copy to sky/engine/bindings-dart/core/dart/DartPersistentValue.cpp
index 61872fbe9498df012e4da6f4c859fd8ac76a8b4d..400f2f00e925e36f55a1b81a208711551570e7f6 100644
--- a/sky/engine/platform/exported/Platform.cpp
+++ b/sky/engine/bindings-dart/core/dart/DartPersistentValue.cpp
@@ -27,27 +27,35 @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
+#include "config.h"
+#include "bindings/core/dart/DartPersistentValue.h"
 
-#include "sky/engine/config.h"
-#include "sky/engine/public/platform/Platform.h"
+#include "bindings/core/dart/DartDOMData.h"
+#include "bindings/core/dart/DartUtilities.h"
 
 namespace blink {
 
-static Platform* s_platform = 0;
-
-void Platform::initialize(Platform* platform)
+DartPersistentValue::DartPersistentValue(Dart_Handle value)
 {
-    s_platform = platform;
+    m_value = Dart_NewPersistentHandle(value);
 }
 
-void Platform::shutdown()
+DartPersistentValue::~DartPersistentValue()
 {
-    s_platform = 0;
+    clear();
 }
 
-Platform* Platform::current()
+void DartPersistentValue::clear()
 {
-    return s_platform;
+    if (!isIsolateAlive())
+        return;
+
+    if (!m_value)
+        return;
+
+    DartIsolateScope scope(isolate());
+    Dart_DeletePersistentHandle(m_value);
+    m_value = 0;
 }
 
-} // namespace blink
+}