Expand overloaded methods and optional parameters in the html library.

tools/dom/templates/html/impl/impl_IDBDatabase.darttemplate

Index: tools/dom/templates/html/impl/impl_IDBDatabase.darttemplate
diff --git a/tools/dom/templates/html/impl/impl_IDBDatabase.darttemplate b/tools/dom/templates/html/impl/impl_IDBDatabase.darttemplate
index fc77a04e9415a53deae83680e8e9ee18e1084e11..143b2bda6cd51f31a28de3c8e5ad4392167bbf17 100644
--- a/tools/dom/templates/html/impl/impl_IDBDatabase.darttemplate
+++ b/tools/dom/templates/html/impl/impl_IDBDatabase.darttemplate
@@ -22,18 +22,29 @@ $(ANNOTATIONS)class $CLASSNAME$EXTENDS$IMPLEMENTS$NATIVESPEC {
   }
 
 $if DART2JS
-  Transaction transaction(storeName_OR_storeNames, String mode) {
+  Transaction transaction(String storeName, String mode) {
     if (mode != 'readonly' && mode != 'readwrite') {
       throw new ArgumentError(mode);
     }
-
-    // TODO(sra): Ensure storeName_OR_storeNames is a string or List<String>,
-    // and copy to JavaScript array if necessary.
-
     // Try and create a transaction with a string mode.  Browsers that expect a
     // numeric mode tend to convert the string into a number.  This fails
     // silently, resulting in zero ('readonly').
-    return _transaction(storeName_OR_storeNames, mode);
+    return _transaction(storeName, mode);
+  }
+
+  Transaction transactionList(List<String> storeNames, String mode) {
+    if (mode != 'readonly' && mode != 'readwrite') {
+      throw new ArgumentError(mode);
+    }
+    List storeNames_1 = convertDartToNative_StringArray(storeNames);
+    return _transaction(storeNames_1, mode);
+  }
+  
+  Transaction transactionStringList(DomStringList storeNames, String mode) {
+    if (mode != 'readonly' && mode != 'readwrite') {
+      throw new ArgumentError(mode);
+    }
+    return _transaction(storeNames_1, mode);
   }
 
   @JSName('transaction')