Click the center of the first non-empty rectangle

Fixes #481.

spec/integration/session_spec.rb

@@ -348,6 +348,7 @@ describe Capybara::Session do
               <form>
                 <input type="checkbox" id="bar">
               </form>
+              <div><a href="#"><i></i>Some link</a></div>
               <script type="text/javascript">
                 var targets = document.getElementsByClassName('target');
                 for (var i = 0; i < targets.length; i++) {
@@ -380,6 +381,11 @@ describe Capybara::Session do
       subject.find(:css, '#one')['data-click-y'].should == '99'
     end
 
+    it 'does not raise an error when an anchor contains empty nodes' do
+      subject.visit('/')
+      lambda { subject.click_link('Some link') }.should_not raise_error(Capybara::Webkit::ClickFailed)
+    end
+
     it 'scrolls an element into view when clicked' do
       subject.visit('/')
       subject.driver.resize_window(200, 200)

src/capybara.js

@@ -146,9 +146,14 @@ Capybara = {
   },
 
   clickPosition: function(node) {
-    var rect = node.getClientRects()[0];
-    if (rect)
-      return CapybaraInvocation.clickPosition(node, rect.left, rect.top, rect.width, rect.height);
+    var rects = node.getClientRects();
+    var rect;
+
+    for (var i = 0; i < rects.length; i++) {
+      rect = rects[i];
+      if (rect.width > 0 && rect.height > 0)
+        return CapybaraInvocation.clickPosition(node, rect.left, rect.top, rect.width, rect.height);
+    }
   },
 
   click: function (index, action) {