Read files in chunks, not relaying on size.

sdk/lib/io/file_impl.dart

Index: sdk/lib/io/file_impl.dart
diff --git a/sdk/lib/io/file_impl.dart b/sdk/lib/io/file_impl.dart
index f6fdb84e1a55f41d09529815d42c9477224d96c7..8ab05f6c5730b2b22159d85da821d1e590107d1a 100644
--- a/sdk/lib/io/file_impl.dart
+++ b/sdk/lib/io/file_impl.dart
@@ -4,14 +4,14 @@
 
 part of dart.io;
 
+// Read the file in blocks of size 64k.
+const int _BLOCK_SIZE = 64 * 1024;
+
 
 class _FileStream extends Stream<List<int>> {
   // Stream controller.
   StreamController<List<int>> _controller;
 
-  // Read the file in blocks of size 64k.
-  final int _blockSize = 64 * 1024;
-
   // Information about the underlying file.
   String _path;
   RandomAccessFile _openedFile;
@@ -76,7 +76,7 @@ class _FileStream extends Stream<List<int>> {
           }
           return null;
         } else {
-          return _openedFile.read(_blockSize);
+          return _openedFile.read(_BLOCK_SIZE);
         }
       })
       .then((block) {
@@ -503,14 +503,13 @@ class _File extends _FileBase implements File {
 
   List<int> readAsBytesSync() {
     var opened = openSync();
-    var length = opened.lengthSync();
-    var result = new Uint8List(length);
-    var read = opened.readListSync(result, 0, length);
-    if (read != length) {
-      throw new FileIOException("Failed to read file");
+    var chunks = new _BufferList();
+    var data;
+    while ((data = opened.readSync(_BLOCK_SIZE)).length > 0) {
+      chunks.add(data);
     }
     opened.closeSync();
-    return result;
+    return chunks.readBytes();
   }
 
   Future<String> readAsString({Encoding encoding: Encoding.UTF_8}) {