build.py -c closure: generate an error of undefined variables

build/closure-compiler/Externs.js

@@ -0,0 +1,50 @@
+// ********************************************
+// This source file serves *ONLY* to avoid some compilation errors when the 
+//      compiler uses the flag:
+//          --jscomp_error undefinedVars
+//
+// In this source are declared all variables from other programs that use 
+//      OpenLayers. This avoids the error of undefined variable for these names.
+//
+// NOTE: The compiler does not include externs files like this in the 
+//      compilation result.
+// ********************************************
+
+// Used in lib/Firebug/firebug.js when gecko_dom
+    var frames;
+
+// Check the console when using Firebug Lite
+    var console;
+
+// Proj4js
+    var Proj4js = {Proj: function(){}};
+
+// Check JSON in lib/OpenLayers/Format/JSON.js
+    var JSON = {};
+
+// Google Maps
+    var GMap2;
+    var G_NORMAL_MAP;
+    var GEvent;
+    var GLatLngBounds = function(){};
+    var GSize = function(x, y){};
+    var GPoint = function(x, y){};
+    var GLatLng = function(lat, lon){};
+    
+// Multimap
+    var MultimapViewer = function(div){};
+    var MMLatLon = function(lat, lon){};
+    var MMPoint = function(x, y){};
+
+//VirtualEarth
+    var VEMap = function(name){};
+    var VEPixel = function(x, y){};
+    var VELatLong = function(lat, lon){};
+    var Msn = {VE:{}};
+
+// Yahoo
+    var YMap = function(div, type, size){};
+    var YGeoPoint = function(lat, lon){};
+    var YCoordPoint = function(x, y){};
+    var YSize = function(w, h){};
+