Add regression test for previously fixed bug.

Closes #388.

R=alanknight@google.com

Review URL: https://chromiumcodereview.appspot.com//1257793003 .
diff --git a/lib/src/chunk_builder.dart b/lib/src/chunk_builder.dart
index 25d36cb..c7ff91b 100644
--- a/lib/src/chunk_builder.dart
+++ b/lib/src/chunk_builder.dart
@@ -511,13 +511,6 @@
 
     // If there is a hard newline within the block, force the surrounding rule
     // for it so that we apply that constraint.
-    // TODO(rnystrom): This does the wrong thing when there is are multiple
-    // block arguments. We correctly force the rule, but then it gets popped
-    // off the writer's stack and it forgets it was forced. Can repro with:
-    //
-    // longFunctionName(
-    //     [longElementName, longElementName, longElementName],
-    //     [short]);
     if (forceSplit) _parent.forceRules();
 
     // Write the split for the block contents themselves.
diff --git a/test/regression/0300/0388.unit b/test/regression/0300/0388.unit
new file mode 100644
index 0000000..a42d366
--- /dev/null
+++ b/test/regression/0300/0388.unit
@@ -0,0 +1,41 @@
+>>>
+class _SimpleNodeValidator {
+  factory _SimpleNodeValidator.allowImages(UriPolicy uriPolicy) {
+    return new _SimpleNodeValidator(uriPolicy,
+        allowedElements: const ['IMG'],
+        allowedAttributes: const [
+      'IMG::align',
+      'IMG::alt',
+      'IMG::border',
+      'IMG::height',
+      'IMG::hspace',
+      'IMG::ismap',
+      'IMG::name',
+      'IMG::usemap',
+      'IMG::vspace',
+      'IMG::width',
+    ],
+        allowedUriAttributes: const ['IMG::src',]);
+  }
+}
+<<<
+class _SimpleNodeValidator {
+  factory _SimpleNodeValidator.allowImages(UriPolicy uriPolicy) {
+    return new _SimpleNodeValidator(uriPolicy, allowedElements: const [
+      'IMG'
+    ], allowedAttributes: const [
+      'IMG::align',
+      'IMG::alt',
+      'IMG::border',
+      'IMG::height',
+      'IMG::hspace',
+      'IMG::ismap',
+      'IMG::name',
+      'IMG::usemap',
+      'IMG::vspace',
+      'IMG::width',
+    ], allowedUriAttributes: const [
+      'IMG::src',
+    ]);
+  }
+}
\ No newline at end of file