Fix Polymer pass from generating code outside goog.loadModule

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=263662505

src/com/google/javascript/jscomp/PolymerClassRewriter.java

@@ -18,6 +18,7 @@
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Preconditions.checkState;
+import static com.google.javascript.jscomp.NodeUtil.isBundledGoogModuleCall;
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Splitter;
@@ -66,6 +67,15 @@ final class PolymerClassRewriter {
     this.propertyRenamingEnabled = propertyRenamingEnabled;
   }
 
+  static boolean isFunctionArgInGoogLoadModule(Node n) {
+    if (!n.isFunction()) {
+      return false;
+    }
+
+    Node parent = n.getParent();
+    return parent != null && isBundledGoogModuleCall(parent);
+  }
+
   /**
    * Rewrites a given call to Polymer({}) to a set of declarations and assignments which can be
    * understood by the compiler.
@@ -141,16 +151,28 @@ void rewritePolymerCall(
     // module scopes are well-supported. If this is not in a module or the global scope it is likely
     // exported.
     if (!isInGlobalOrModuleScope && !cls.target.isGetProp()) {
-      Node scriptOrModuleNode =
-          NodeUtil.getEnclosingNode(parent, node -> node.isScript() || node.isModuleBody());
-      if (scriptOrModuleNode.isModuleBody()
-          && scriptOrModuleNode.getParent().getBooleanProp(Node.GOOG_MODULE)) {
+      Node enclosingNode =
+          NodeUtil.getEnclosingNode(
+              parent,
+              node ->
+                  node.isScript() || node.isModuleBody() || isFunctionArgInGoogLoadModule(node));
+      if (enclosingNode.isModuleBody()
+          && enclosingNode.getParent().getBooleanProp(Node.GOOG_MODULE)) {
         // The goog.module('ns'); call must remain the first statement in the module.
-        Node insertionPoint = getInsertionPointForGoogModule(scriptOrModuleNode);
-        scriptOrModuleNode.addChildrenAfter(statements, insertionPoint);
-      } else {
-        scriptOrModuleNode.addChildrenToFront(statements);
-        compiler.reportChangeToChangeScope(NodeUtil.getEnclosingScript(scriptOrModuleNode));
+        Node insertionPoint = getInsertionPointForGoogModule(enclosingNode);
+        enclosingNode.addChildrenAfter(statements, insertionPoint);
+      } else if (enclosingNode.isScript()) {
+        enclosingNode.addChildrenToFront(statements);
+        compiler.reportChangeToChangeScope(NodeUtil.getEnclosingScript(enclosingNode));
+      } else if (enclosingNode.isFunction()) {
+        Node functionBlock = enclosingNode.getLastChild();
+        Node insertionPoint = getInsertionPointForGoogModule(functionBlock);
+        // Node insertionPoint will be null here if functionBlock does not contain a goog.module()
+        // Missing goog.module inside the loadModule's functionBlock is semantically incorrect
+        // That will cause the compiler to crash in closureRewriteModule pass.
+        if (insertionPoint != null) {
+          functionBlock.addChildrenAfter(statements, insertionPoint);
+        }
       }
     } else {
       Node beforeRoot = exprRoot.getPrevious();
@@ -996,7 +1018,6 @@ private static boolean isParamLiteral(String param) {
   }
 
   private static Node getInsertionPointForGoogModule(Node moduleBody) {
-    checkArgument(moduleBody.isModuleBody(), moduleBody);
     Node insertionPoint = moduleBody.getFirstChild(); // goog.module('ns');
     Node next = insertionPoint.getNext();
     while ((NodeUtil.isNameDeclaration(next)

test/com/google/javascript/jscomp/PolymerClassRewriterTest.java

@@ -79,6 +79,27 @@ public void setUp() throws Exception {
 
   // TODO(jlklein): Add tests for non-global definitions, interface externs, read-only setters, etc.
 
+  @Test
+  public void testPolymerWriterGeneratesCodeInsideLoadModule() {
+    inGlobalScope = false;
+    test(
+        lines(
+            "goog.loadModule(function(exports) {",
+            "  goog.module('ytu.app.ui.shared.YtuIcon');",
+            "  YtuIcon = Polymer({is: 'ytu-icon' });",
+            "  exports = YtuIcon;",
+            "  return exports;",
+            "})"),
+        lines(
+            "goog.loadModule(function(exports) {",
+            "  goog.module('ytu.app.ui.shared.YtuIcon');",
+            "  var YtuIcon = function(){}",
+            "  YtuIcon = Polymer(/** @lends {YtuIcon.prototype} */ {is:\"ytu-icon\"});",
+            "  exports = YtuIcon;",
+            "  return exports;",
+            "})"));
+  }
+
   @Test
   public void testVarTarget() {
     test(