Fix crash when calling chrome.tabs.move({index:-1}).

chrome/test/data/extensions/api_test/tabs/basics/move.html

 <script src="tabs_util.js"></script>
 
 <script>
 var firstWindowId;
 var secondWindowId;
 var moveTabIds = {};
 
 chrome.test.runTests([
   // Do a series of moves so that we get the following
   //
@@ skipping 62 matching lines @@
 
   function remove() {
     chrome.tabs.remove(moveTabIds["d"], pass(function() {
       chrome.tabs.getAllInWindow(secondWindowId,
                                  pass(function(tabs) {
         assertEq(2, tabs.length);
         assertEq(pageUrl("b"), tabs[0].url);
         assertEq("chrome://newtab/", tabs[1].url);
       }));
     }));
+  },
+
+  // Make sure we don't crash when the index is out of range.
+  function moveToInvalidTab() {
+    var error_msg = "Invalid value for argument 2. Property 'index': " +
+        "Value must not be less than 0.";
+    try {
+      chrome.tabs.move(moveTabIds['b'], {index: -1}, function(tab) {
+        chrome.test.fail("Moved a tab to an invalid index");
+      });
+    } catch (e) {
+      assertEq(error_msg, e.message);
+    }
+    chrome.tabs.move(moveTabIds['b'], {index: 10000}, pass(function(tabB) {
+      assertEq(1, tabB.index);
+    }));
   }
 ]);
 </script>