Add a flag to prohibit plurals/genders that don't take up the whole string.

pkg/intl/test/message_extraction/embedded_plural_text_before.dart

Index: pkg/intl/test/message_extraction/embedded_plural_text_before.dart
diff --git a/pkg/intl/test/message_extraction/embedded_plural_text_before.dart b/pkg/intl/test/message_extraction/embedded_plural_text_before.dart
new file mode 100644
index 0000000000000000000000000000000000000000..854b4958757750a716a39daaf7b1fa42a6449154
--- /dev/null
+++ b/pkg/intl/test/message_extraction/embedded_plural_text_before.dart
@@ -0,0 +1,15 @@
+// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/// A test library that should fail because there is a plural with text
+/// before the plural expression.
+library embedded_plural_text_before;
+
+import "package:intl/intl.dart";
+
+embeddedPlural(n) => Intl.message(
+    "There are ${Intl.plural(n, zero: 'nothing', one: 'one', other: 'some')}.",
+    name: 'embeddedPlural',
+    desc: 'An embedded plural',
+    args: [n]);