Access to imports in the VM's runtime mirrors. Extend test coverage of the source mirrors.

tests/lib/mirrors/stringify.dart

Index: tests/lib/mirrors/stringify.dart
diff --git a/tests/lib/mirrors/stringify.dart b/tests/lib/mirrors/stringify.dart
index c848f93464587c6129a0c055ce8bfb8bc2d596ca..067769a1757f44a90e05cfde4b434f8aba34dfa6 100644
--- a/tests/lib/mirrors/stringify.dart
+++ b/tests/lib/mirrors/stringify.dart
@@ -114,6 +114,39 @@ stringifyMethod(MethodMirror method) {
   return 'Method($buffer)';
 }
 
+stringifyDependencies(LibraryMirror l) {
+  n(s) => s is Symbol ? MirrorSystem.getName(s) : s;
+  compareDep(a, b) =>
+      n(a.targetLibrary.simpleName).compareTo(n(b.targetLibrary.simpleName));
+  compareCom(a, b) => n(a.identifier).compareTo(n(b.identifier));
+  compareFirst(a, b) => a[0].compareTo(b[0]);
+  sortBy(c, p) => new List.from(c)..sort(p);
+
+  var buffer = new StringBuffer();
+  sortBy(l.libraryDependencies, compareDep).forEach((dep) {
+    if (dep.isImport) buffer.write('import ');
+    if (dep.isExport) buffer.write('export ');
+    buffer.write(n(dep.targetLibrary.simpleName));
+    if (dep.prefix != null) buffer.write(' as ${n(dep.prefix)}');
+    buffer.write('\n');
+
+    List flattenedCombinators = new List();
+    dep.combinators.forEach((com) {
+      com.identifiers.forEach((ident) {
+        flattenedCombinators.add([n(ident), com.isShow, com.isHide]);
+      });
+    });
+    sortBy(flattenedCombinators, compareFirst).forEach((triple) {
+      buffer.write(' ');
+      if (triple[1]) buffer.write('show ');
+      if (triple[2]) buffer.write('hide ');
+      buffer.write(triple[0]);
+      buffer.write('\n');
+    });
+  });
+  return buffer.toString();
+}
+
 stringify(value) {
   if (value is Map) return stringifyMap(value);
   if (value is Iterable) return stringifyIterable(value);