Fixes "Large border radius" bug in chrome

Author: Grom-S

src/Parse.js

@@ -681,9 +681,19 @@ _html2canvas.Parse = function (images, options, cb) {
     brh = borderRadius[2][0],
     brv = borderRadius[2][1],
     blh = borderRadius[3][0],
-    blv = borderRadius[3][1],
-
-    topWidth = width - trh,
+    blv = borderRadius[3][1];
+
+    var halfHeight = Math.floor(height / 2);
+    tlh = tlh > halfHeight ? halfHeight : tlh;
+    tlv = tlv > halfHeight ? halfHeight : tlv;
+    trh = trh > halfHeight ? halfHeight : trh;
+    trv = trv > halfHeight ? halfHeight : trv;
+    brh = brh > halfHeight ? halfHeight : brh;
+    brv = brv > halfHeight ? halfHeight : brv;
+    blh = blh > halfHeight ? halfHeight : blh;
+    blv = blv > halfHeight ? halfHeight : blv;
+
+    var topWidth = width - trh,
     rightHeight = height - brv,
     bottomWidth = width - brh,
     leftHeight = height - blv;