Fix file tests.

tests/standalone/src/FileTest.dart

Index: tests/standalone/src/FileTest.dart
diff --git a/tests/standalone/src/FileTest.dart b/tests/standalone/src/FileTest.dart
index bf72b191a9e2a8c0a088d0e4a47384e1d3b87fcc..e90244a9bdfa4ca63d9dcb2d2d98a27b4e3d5fe8 100644
--- a/tests/standalone/src/FileTest.dart
+++ b/tests/standalone/src/FileTest.dart
@@ -915,7 +915,7 @@ class FileTest {
     f.readAsTextHandler = (text) {
       Expect.isTrue(text.endsWith("42 bytes."));
       Expect.equals(42, text.length);
-      var name = getFilename("tests/standalone/src/read_as_text.dat");
+      var name = getDataFilename("tests/standalone/src/read_as_text.dat");
       var f = new File(name);
       f.errorHandler = (e) => Expect.fail("No errors expected");
       f.readAsText('UTF-8');
@@ -948,7 +948,7 @@ class FileTest {
     var text = new File(name).readAsTextSync();
     Expect.isTrue(text.endsWith("42 bytes."));
     Expect.equals(42, text.length);
-    name = getFilename("tests/standalone/src/read_as_text.dat");
+    name = getDataFilename("tests/standalone/src/read_as_text.dat");
     text = new File(name).readAsTextSync();
     Expect.equals(6, text.length);
     var expected = [955, 120, 46, 32, 120, 10];
@@ -986,7 +986,7 @@ class FileTest {
     var line = lines[0];
     Expect.isTrue(line.endsWith("42 bytes."));
     Expect.equals(42, line.length);
-    name = getFilename("tests/standalone/src/readline_test1.dat");
+    name = getDataFilename("tests/standalone/src/readline_test1.dat");
     lines = new File(name).readAsLinesSync();
     Expect.equals(10, lines.length);
   }
@@ -1064,6 +1064,9 @@ class FileTest {
   static String getFilename(String path) =>
       new File(path).existsSync() ? path : 'runtime/' + path;
 
+  static String getDataFilename(String path) =>
+      new File(path).existsSync() ? path : '../' + path;
+
   // Main test entrypoint.
   static testMain() {
     testRead();