Allow multiple dart <script> tags in .sky files

sky/tests/modules/multiple-scripts.sky

Index: sky/tests/modules/multiple-scripts.sky
diff --git a/sky/tests/modules/multiple-scripts.sky b/sky/tests/modules/multiple-scripts.sky
new file mode 100644
index 0000000000000000000000000000000000000000..ce74e6a245ce0fdb79a630a891dd7e4cc66484c3
--- /dev/null
+++ b/sky/tests/modules/multiple-scripts.sky
@@ -0,0 +1,19 @@
+<sky>
+<div id='test'>FAIL</div>
+<script>
+import "dart:sky" as sky;
+
+void main () {
+    sky.document.getElementById('test').textContent = 'PASS';
+}
+</script>
+<script>
+// Each script is a separate dart library.
+import "dart:sky" as sky;
+import "dart:sky.internals" as internals;
+
+void main () {
+  internals.notifyTestComplete(sky.document.getElementById('test').textContent);
+}
+</script>
+</sky>