Read EnableExtensionManager and EnableProfileMigrator from the XRE section

of the .xulapp file instead of from the App section since these are really
properties of the XRE.

toolkit/xre/nsAppRunner.cpp

@@ -446,7 +446,7 @@ static const nsXREAppData* LoadAppData(const char* appDataFile)
   };
   char buf[2];
   for (i=0; i<2; ++i) {
-    rv = parser.GetString("App", boolean_fields[i].key, buf, sizeof(buf));
+    rv = parser.GetString("XRE", boolean_fields[i].key, buf, sizeof(buf));
     if (NS_SUCCEEDED(rv))
       *(boolean_fields[i].value) =
           buf[0] == '1' || buf[0] == 't' || buf[0] == 'T';