Add include method definitions

chai-dom lets you chain like this:

expect(element).not.to.contain.text('Open');

Extend interface Include to reflect this.

chai-dom/chai-dom.d.ts

@@ -24,6 +24,14 @@ declare namespace Chai {
         value(text: string): Assertion;
 
     }
+    
+    interface Include {
+        
+        text(text: string|string[]): Assertion;
+        
+        html(text: string|string[]): Assertion;
+        
+    }
 
 }