Display MathML fallback content when it is specified and take into account inline/display modes for…

Source/core/css/mathml.css

Index: Source/core/css/mathml.css
diff --git a/Source/core/dom/custom/CustomElementMicrotaskElementStep.cpp b/Source/core/css/mathml.css
similarity index 66%
copy from Source/core/dom/custom/CustomElementMicrotaskElementStep.cpp
copy to Source/core/css/mathml.css
index 7e76e0ce6e2bbda8cdc46456608bff6c25b12aa6..26f3ff4a063e4a5895e092c947903dafdf76e714 100644
--- a/Source/core/dom/custom/CustomElementMicrotaskElementStep.cpp
+++ b/Source/core/css/mathml.css
@@ -1,4 +1,6 @@
 /*
+ * The default style sheet used to render MathML.
+ *
  * Copyright (C) 2014 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -28,30 +30,30 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include "config.h"
-#include "core/dom/custom/CustomElementMicrotaskElementStep.h"
-
-#include "core/dom/custom/CustomElementCallbackQueue.h"
+@namespace "http://www.w3.org/1998/Math/MathML";
 
-namespace WebCore {
-
-PassOwnPtr<CustomElementMicrotaskElementStep> CustomElementMicrotaskElementStep::create(CustomElementCallbackQueue* queue)
-{
-    ASSERT(queue);
-    return adoptPtr(new CustomElementMicrotaskElementStep(queue));
+/* By default, we only display the MathML formulas without any formatting other than the one specified by the display attribute. */
+math {
+    display: inline;
 }
-
-static const CustomElementCallbackQueue::ElementQueueId kMicrotaskQueueId = 0;
-
-CustomElementMicrotaskElementStep::CustomElementMicrotaskElementStep(CustomElementCallbackQueue* queue)
-    : m_queue(queue)
-{
-    m_queue->setOwner(kMicrotaskQueueId);
+math[display="block"] {
+    display: block;
+    text-align: center;
 }
 
-CustomElementMicrotaskStep::Result CustomElementMicrotaskElementStep::process()
-{
-    return m_queue->processInElementQueue(kMicrotaskQueueId) ? DidWork : Result(0);
+/* We only display the second child of a <semantics> element, which is its first annotation. */
+semantics > * {

[esprehn, 2014/01/15 20:59:59]

This is bad, it ends up in the universal rules so we have to match it all the
time.

+    display: none;
+}
+semantics > *:first-child + annotation,
+semantics > *:first-child + annotation-xml {

[esprehn, 2014/01/15 20:59:59]

This is bad, it means we will invalidate a sibling of every SubtreeStyleChange
all the time because of the + operator.

+    display: inline-block;
 }
 
-} // namespace WebCore
+/* If an alttext attribute is specified, we replace the MathML formula with that text. */
+math[alttext] * {

[esprehn, 2014/01/15 20:59:59]

Another universal rule, it's going to add a rule to all elements in every page.

+    display: none;
+}
+math[alttext]::after {

[esprehn, 2014/01/15 20:59:59]

This is another universal rule :(

+    content: attr(alttext);
+}