Bug 927911: Don't try to attach SelectionHandler carets to disabled input elements, r=margaret

mobile/android/chrome/content/browser.js

@@ -4305,10 +4305,11 @@ var BrowserEventHandler = {
             this._sendMouseEvent("mousedown", element, x, y);
             this._sendMouseEvent("mouseup",   element, x, y);
 
-            // See if its a input element
-            if ((element instanceof HTMLInputElement && element.mozIsTextField(false)) ||
-                (element instanceof HTMLTextAreaElement))
-               SelectionHandler.attachCaret(element);
+            // See if its an input element, and it isn't disabled
+            if (!element.disabled &&
+                ((element instanceof HTMLInputElement && element.mozIsTextField(false)) ||
+                (element instanceof HTMLTextAreaElement)))
+              SelectionHandler.attachCaret(element);
 
             // scrollToFocusedInput does its own checks to find out if an element should be zoomed into
             BrowserApp.scrollToFocusedInput(BrowserApp.selectedBrowser);