Adds new scrolling functionality

Author: Starefossen

intro.js

@@ -297,13 +297,33 @@
       //change to new intro item
       targetElement.className += " introjs-relativePosition";
     }
-
-    //scroll the page to the element position
-    if (typeof(targetElement.scrollIntoViewIfNeeded) === "function") {
-      //awesome method guys: https://bugzilla.mozilla.org/show_bug.cgi?id=403510
-      //but I think this method has some problems with IE < 7.0, I should find a proper failover way
-      targetElement.scrollIntoViewIfNeeded();
-    }
+    
+    if (!elementInViewport(targetElement)) {
+      var rect = targetElement.getBoundingClientRect()
+          top = rect.bottom-rect.height,
+          bottom = rect.bottom-window.innerHeight;
+      
+      // Scroll up
+      if (top < 0) {
+        window.scrollBy(0, top-30); // 30px padding from edge to look nice
+      
+      // Scroll down
+      } else {
+        window.scrollBy(0, bottom+100); // 70px + 30px padding from edge to look nice
+      }
+    }    
+  }
+  
+  // http://stackoverflow.com/questions/123999/how-to-tell-if-a-dom-element-is-visible-in-the-current-viewport
+  function elementInViewport(el) {
+    var rect = el.getBoundingClientRect();
+    
+    return (
+      rect.top >= 0 &&
+      rect.left >= 0 &&
+      (rect.bottom+80) <= window.innerHeight && // add 80 to get the text right
+      rect.right <= window.innerWidth 
+    );
   }
 
   /**