Roll forward "Use package:stack_trace in unittest."

pkg/unittest/lib/src/utils.dart

Index: pkg/unittest/lib/src/utils.dart
diff --git a/pkg/unittest/lib/src/utils.dart b/pkg/unittest/lib/src/utils.dart
index 6442ac43897395373b96085e2444a1b512e1787c..e10c597d3f0bda8623e088418d86b5f287e07aac 100644
--- a/pkg/unittest/lib/src/utils.dart
+++ b/pkg/unittest/lib/src/utils.dart
@@ -46,3 +46,24 @@ String _escapeChar(String ch) {
     return ch;
 }
 
+/** Indent each line in [str] by two spaces. */
+String indent(String str) =>
+  str.replaceAll(new RegExp("^", multiLine: true), "  ");
+
+/** A pair of values. */
+class Pair<E, F> {
+  E first;
+  F last;
+
+  Pair(this.first, this.last);
+
+  String toString() => '($first, $last)';
+
+  bool operator==(other) {
+    if (other is! Pair) return false;
+    return other.first == first && other.last == last;
+  }
+
+  int get hashCode => first.hashCode ^ last.hashCode;
+}
+