Make writes consistent across socket and file synchronous/asynchronus writes in terms of truncation…

sdk/lib/io/common.dart

Index: sdk/lib/io/common.dart
===================================================================
--- sdk/lib/io/common.dart	(revision 24619)
+++ sdk/lib/io/common.dart	(working copy)
@@ -97,23 +97,12 @@
 }
 
 // Ensure that the input List can be serialized through a native port.
-// Only builtin Lists can be serialized through. If user-defined Lists
-// get here, the contents is copied to a Uint8List. This has the added
+// Only Int8List and Uint8List Lists are serialized directly.
+// All other lists are first copied into a Uint8List. This has the added
 // benefit that it is faster to access from the C code as well.
-_BufferAndStart _ensureFastAndSerializableData(
+_BufferAndStart _ensureFastAndSerializableByteData(
     List buffer, int start, int end) {
-  if (buffer is Uint8List ||
-      buffer is Int8List ||
-      buffer is Uint16List ||
-      buffer is Int16List ||
-      buffer is Uint32List ||
-      buffer is Int32List ||
-      buffer is Uint64List ||
-      buffer is Int64List ||
-      buffer is ByteData ||
-      buffer is Float32List ||
-      buffer is Float64List ||
-      _BufferUtils._isBuiltinList(buffer)) {
+  if (buffer is Uint8List || buffer is Int8List) {
     return new _BufferAndStart(buffer, start);
   }
   int length = end - start;
@@ -131,37 +120,6 @@
 }
 
 
-_BufferAndStart _ensureFastAndSerializableByteData(
-    List buffer, int start, int end) {
-  if (buffer is Uint8List) {
-    return new _BufferAndStart(buffer, start);
-  }
-  int length = end - start;
-  var newBuffer = new Uint8List(length);
-  int j = start;
-  for (int i = 0; i < length; i++) {
-    int value = buffer[j];
-    if (value is! int ||
-        value < 0 || 255 < value) {
-      throw new ArgumentError(
-          "List element is not a byte value (value $value at index $j)");
-    }
-    newBuffer[i] = value;
-    j++;
-  }
-  return new _BufferAndStart(newBuffer, 0);
-}
-
-
-// TODO(ager): The only reason for the class here is that
-// we cannot patch a top-level function.
-class _BufferUtils {
-  // Check if a List is a builtin VM List type. Returns true
-  // if the List is a builtin VM List type and false if it is
-  // a user defined List type.
-  external static bool _isBuiltinList(List buffer);
-}
-
 class _IOCrypto {
   external static Uint8List getRandomBytes(int count);
 }