Fix for issue #1320; allow null strings to be passed for second parameter to gwtOnLoad, which indicates the module is being unloaded.

Patch by: jat
Review by: scottb


git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@1238 8db76d5a-ed1c-0410-87a9-c151d255dfc7
diff --git a/dev/mac/src/com/google/gwt/dev/shell/mac/BrowserWidgetSaf.java b/dev/mac/src/com/google/gwt/dev/shell/mac/BrowserWidgetSaf.java
index 6d148d1..d23cab8 100644
--- a/dev/mac/src/com/google/gwt/dev/shell/mac/BrowserWidgetSaf.java
+++ b/dev/mac/src/com/google/gwt/dev/shell/mac/BrowserWidgetSaf.java
@@ -110,7 +110,8 @@
         if (!LowLevelSaf.isObject(jsargs[0])) {
           return jsFalse;
         }
-        if (!LowLevelSaf.isString(jsargs[1])) {
+        if (!LowLevelSaf.isNull(jsargs[1])
+            && !LowLevelSaf.isString(jsargs[1])) {
           return jsFalse;
         }
         String moduleName = LowLevelSaf.coerceToString(execState, jsargs[1]);