Move non-canvas supported fallback to seperate file

Gruntfile.js

@@ -21,7 +21,7 @@ module.exports = function(grunt) {
         concat: {
             dist: {
                 src: [
-                    'src/promise.js', 'src/**/*.js'
+                    'src/promise.js', 'src/fallback.js', 'src/**/*.js'
                 ],
                 dest: 'build/<%= pkg.name %>.js'
             },

src/core.js

@@ -1,12 +1,5 @@
 var html2canvasNodeAttribute = "data-html2canvas-node";
 
-if (typeof(Object.create) !== "function" || typeof(document.createElement("canvas").getContext) !== "function") {
-    window.html2canvas = function() {
-        return Promise.reject("No canvas support");
-    };
-    return;
-}
-
 window.html2canvas = function(nodeList, options) {
     options = options || {};
     if (options.logging) {

src/fallback.js

@@ -0,0 +1,6 @@
+if (typeof(Object.create) !== "function" || typeof(document.createElement("canvas").getContext) !== "function") {
+    window.html2canvas = function() {
+        return Promise.reject("No canvas support");
+    };
+    return;
+}