Fix void foo(..) => ... to use { } instead.

sdk/lib/io/bytes_builder.dart

Index: sdk/lib/io/bytes_builder.dart
diff --git a/sdk/lib/io/bytes_builder.dart b/sdk/lib/io/bytes_builder.dart
index 610c50a74638e5c8d1ab3844f8522c16814ae9a3..2882402b641bc1171d41adb0d5d04a5587ddbb2c 100644
--- a/sdk/lib/io/bytes_builder.dart
+++ b/sdk/lib/io/bytes_builder.dart
@@ -113,7 +113,7 @@ class _CopyingBytesBuilder implements BytesBuilder {
     _length = required;
   }
 
-  void addByte(int byte) => add([byte]);
+  void addByte(int byte) { add([byte]); }
 
   List<int> takeBytes() {
     if (_buffer == null) return new Uint8List(0);
@@ -163,7 +163,7 @@ class _BytesBuilder implements BytesBuilder {
     _length += bytes.length;
   }
 
-  void addByte(int byte) => add([byte]);
+  void addByte(int byte) { add([byte]); }
 
   List<int> takeBytes() {
     if (_chunks.length == 0) return new Uint8List(0);