Add delimiter sizing

Summary:
Make delimiter sizing work. This involved
 - Adding the symbols for the remaining delimiters (like `\lfloor` and `\{`)
 - Adding metrics for the size1, size2, size3, and size4 fonts
 - Parsing delimiter sizing functions
 - Using the big fonts when possible, otherwise building large copies of the
   delimiters from scratch

Test Plan:
 - See that
   `\bigl\uparrow\Bigl\downarrow\biggl\updownarrow\Biggl\Uparrow
    \Biggr\Downarrow\biggr\Updownarrow\bigm/\Bigm\backslash\biggm|
    \Biggm|\big\lceil\Big\rceil\bigg\langle\Bigg\rangle\bigl(\Bigl)
    \biggl[\Biggl]\Biggr\{\biggr\}\Bigr\lfloor\bigr\rfloor`
   parses correctly (this contains all of the delimiters, and all of the sizing
   modes)
 - See that the huxley tests didn't change, and the new one looks good
 - See the normal tests work

Reviewers: alpert

Reviewed By: alpert

Differential Revision: http://phabricator.khanacademy.org/D7844

test/huxley/DelimiterSizing.hux/record.json

@@ -0,0 +1,5 @@
+[
+  {
+    "action": "screenshot"
+  }
+]

test/huxley/Huxleyfile.json

@@ -93,5 +93,11 @@
         "name": "Lap",
         "screenSize": [1024, 768],
         "url": "http://localhost:7936/test/huxley/test.html?m=ab\\llap{f}cd\\rlap{g}h"
+    },
+
+    {
+        "name": "DelimiterSizing",
+        "screenSize": [1024, 768],
+        "url": "http://localhost:7936/test/huxley/test.html?m=\\bigl\\uparrow\\Bigl\\downarrow\\biggl\\updownarrow\\Biggl\\Uparrow\\Biggr\\Downarrow\\biggr\\langle\\Bigr\\}\\bigr\\rfloor"
     }
 ]

test/katex-tests.js

@@ -626,3 +626,44 @@ describe("A tie parser", function() {
         expect(parse[2].type).toMatch("spacing");
     });
 });
+
+describe("A delimiter sizing parser", function() {
+    var normalDelim = "\\bigl |";
+    var notDelim = "\\bigl x";
+    var bigDelim = "\\Biggr \\langle";
+
+    it("should parse normal delimiters", function() {
+        expect(function() {
+            parseTree(normalDelim);
+            parseTree(bigDelim);
+        }).not.toThrow();
+    });
+
+    it("should not parse not-delimiters", function() {
+        expect(function() {
+            parseTree(notDelim);
+        }).toThrow();
+    });
+
+    it("should produce a delimsizing", function() {
+        var parse = parseTree(normalDelim)[0];
+
+        expect(parse.type).toMatch("delimsizing");
+    });
+
+    it("should produce the correct direction delimiter", function() {
+        var leftParse = parseTree(normalDelim)[0];
+        var rightParse = parseTree(bigDelim)[0];
+
+        expect(leftParse.value.type).toMatch("open");
+        expect(rightParse.value.type).toMatch("close");
+    });
+
+    it("should parse the correct size delimiter", function() {
+        var smallParse = parseTree(normalDelim)[0];
+        var bigParse = parseTree(bigDelim)[0];
+
+        expect(smallParse.value.size).toEqual(1);
+        expect(bigParse.value.size).toEqual(4);
+    });
+});