Somehow manage to fix the sizing bugs

Summary:
Remove a single `vertical-align: top`, and somewhow it now works. May
the gods of CSS have mercy on us. Also added some tests.

Test Plan:
 - See that the huxley tests don't have any changes
 - See that the new huxley screenshots look reasonable
 - Run the normal tests and see that they work

Reviewers: alpert

Reviewed By: alpert

Differential Revision: http://phabricator.khanacademy.org/D7494

static/katex.less

@@ -163,7 +163,6 @@ big parens
 
     .baseline-align-hack-outer() {
         display: inline-block;
-        vertical-align: top;
     }
 
     .baseline-align-hack-middle() {
@@ -184,7 +183,8 @@ big parens
         margin-left: 0.05em;
 
         .msup,
-        .msub {
+        .msub,
+        .fix-ie {
             .baseline-align-hack-middle;
             position: relative;
 
@@ -192,6 +192,10 @@ big parens
                 .baseline-align-hack-inner;
             }
         }
+
+        .fix-ie {
+            display: inline-block;
+        }
     }
 
     .mfrac {
@@ -199,7 +203,8 @@ big parens
 
         .mfracnum,
         .mfracmid,
-        .mfracden {
+        .mfracden,
+        .fix-ie {
             .baseline-align-hack-middle;
             position: relative;
             text-align: center;
@@ -209,6 +214,10 @@ big parens
             }
         }
 
+        .fix-ie {
+            display: inline-block;
+        }
+
         .mfracmid > span {
             width: 100%;