Add ability to update globals by setting new input.

docs/components.md

@@ -483,7 +483,7 @@ this.setStateDirty('numbers');
 
 ### `this.input`
 
-The current input for the component.  Setting `this.input` will result in the component being re-rendered.
+The current input for the component. Setting `this.input` will result in the component being re-rendered. If a `$global` property is set the `out.global` will also be updated during the re-render, otherwise the existing `$global` is used.
 
 ## Variables
 

src/components/Component.js

@@ -437,6 +437,9 @@ Component.prototype = componentProto = {
 
         if (this.___input === undefined) {
             this.___input = newInput;
+            if (newInput.$global) {
+                this.___global = newInput.$global;
+            }
         }
 
         return newInput;

test/autotests/components-browser/input-global/index.marko

@@ -0,0 +1,6 @@
+class {
+}
+
+<div key="current">
+    Pathname: ${out.global.pathname}
+</div>

test/autotests/components-browser/input-global/test.js

@@ -0,0 +1,20 @@
+var expect = require('chai').expect;
+
+module.exports = function(helpers) {
+    var component = helpers.mount(require('./index.marko'), {
+        $global: {
+            pathname:'/'
+        }
+    });
+
+    expect(component.getEl('current').innerHTML).to.equal('Pathname: /');
+
+    component.input = {
+        $global: {
+            pathname: '/test'
+        }
+    }
+    component.update();
+
+    expect(component.getEl('current').innerHTML).to.equal('Pathname: /test');
+};