Add a few more edge cases to CSS serialization test.

third_party/WebKit/Source/web/tests/data/frameserializer/css/css_test_page.html

Index: third_party/WebKit/Source/web/tests/data/frameserializer/css/css_test_page.html
diff --git a/third_party/WebKit/Source/web/tests/data/frameserializer/css/css_test_page.html b/third_party/WebKit/Source/web/tests/data/frameserializer/css/css_test_page.html
index bf2b3d1048ec2f7b7b79c9986732137782ff8f4b..97baa8a70d1937d1b49c9c26d437cd389cf8a77a 100644
--- a/third_party/WebKit/Source/web/tests/data/frameserializer/css/css_test_page.html
+++ b/third_party/WebKit/Source/web/tests/data/frameserializer/css/css_test_page.html
@@ -6,6 +6,12 @@
 
 <link rel="stylesheet" type="text/css" href="link_styles.css" />
 <link rel="stylesheet" type="text/css" href="encoding.css" />
+<!-- This data URL contains a style referring to an image that should not be
+     serialized and a fuchsia color background -->
+<link rel="stylesheet" type="text/css" 
+      href="data:text/css;charset=utf-8;base64,I2RpdkZ1Y2hzaWEgew0KICBiYWNrZ3JvdW5kLWltYWdlOiB1cmwoJ2RvX25vdF9zZXJpYWxpemUucG5nJyk7DQogIGJhY2tncm91bmQtY29sb3I6ICNGRjAwRkY7DQp9" />

[carlosk, 2016/10/11 23:08:54]

I'm unsure of the correct HTML style, especially in this line.

[Łukasz Anforowicz, 2016/10/11 23:30:37]

Hmmm... non-base64-encoded form of the data: URI is only marginally more
readable:

data:text/css;charset=utf-8,%23divFuchsia%20%7B%0D%0A%20%20background-image%3A%20url%28%27do_not_serialize.png%27%29%3B%0D%0A%20%20background-color%3A%20%23FF00FF%3B%0D%0A%7D

So, I guess I am fine with just having base64-encoded data URI above.

One way to help the reader, might be to add a decoded/expanded form in a
comment.  I don't feel particularily strongly about this though...


I wonder if it might be worth it to add a subresource with a unique link to the
CSS in the data: URI (similar to how we test presence of pink_background.png
coming from the inline <style> tag).

[carlosk, 2016/10/12 00:41:30]

Replaced with an escaped sequence instead of base64.
Done that too.
I tried this with a relative URL and it didn't work. But it did indeed work
using an absolute URL to an image so I added this extra element too.

+<!-- This should be skipped for already being included from another frame -->
+<link rel="stylesheet" type="text/css" href="included_in_another_frame.css" />
 
 <style>
 @import url('import_styles.css');
@@ -60,6 +66,9 @@ ol {
   }
 }
 
+// Tries to import a resource that was already previously linked.
+@import url('link_styles.css');
+
 </style>
 
 <script>
@@ -121,6 +130,11 @@ This div has a pink image as its background.
 This div has a brown image as its background.
 </div>
 
+<!-- Style is in linked data URL -->
+<div id='divFuchsia'>
+This div has a fuchsia image as its background.
+</div>
+
 Unordered list:<br>
 <ul>
   <li>Blue</li>