Complete rendering even if capture selector cannot be found so failing tests...

Complete rendering even if capture selector cannot be found so failing tests can be better debugged. In screenshot testing lib.

tests/lib/screenshot-testing/support/page-renderer.js

@@ -280,7 +280,8 @@ PageRenderer.prototype.capture = function (outputPath, callback, selector) {
         }, selector);
 
         if (!result) {
-            throw new Error("Cannot find element " + selector);
+            console.log("Cannot find element " + selector);
+            return;
         }
 
         if (result && result.__isCallError) {
@@ -290,8 +291,10 @@ PageRenderer.prototype.capture = function (outputPath, callback, selector) {
         if (null === result.left
             || null === result.top
             || null === result.bottom
-            || null === result.right) {
-            throw new Error("Element(s) " + selector + " found but none is visible");
+            || null === result.right
+        ) {
+            console.log("Element(s) " + selector + " found but none is visible");
+            return;
         }
 
         page.clipRect = result;