Added synchronous socket implementation to dart:io.

runtime/include/dart_api.h

Index: runtime/include/dart_api.h
diff --git a/runtime/include/dart_api.h b/runtime/include/dart_api.h
index 4a034a24ca76235bc57b87c2ed89d69a3ef0df61..7e7e890d91a842433f7c1c28e8102dc1e2026a92 100644
--- a/runtime/include/dart_api.h
+++ b/runtime/include/dart_api.h
@@ -387,6 +387,18 @@ DART_EXPORT Dart_Handle Dart_PropagateError(Dart_Handle handle);
 /* TODO(turnidge): Should this really return an error handle? */
 /* Consider just terminating. */
 
+/**
+ * Propagates error if 'handle' is an error handle.
+ *
+ * Provided for convenience.
+ */
+#define DART_CHECK_VALID_AND_PROPAGATE(handle)                                 \
+  {                                                                            \
+    if (Dart_IsError((handle))) {                                              \
+      Dart_PropagateError(handle);                                             \

[zra, 2017/04/10 21:39:43]

Dart_PropagateError is actually a little bit dangerous because it skips over C++
frames without giving any opportunity for cleanup, so I don't think we should be
making it any more convenient to use.

[bkonyi, 2017/04/11 01:30:51]

Ah okay, good to know. Removed.

+    }                                                                          \
+  }
+
 /* Internal routine used for reporting error handles. */
 DART_EXPORT void _Dart_ReportErrorHandle(const char* file,
                                          int line,