Upgrade the source to use ES6 syntax including classes, import and static properties (#679)

* Add babel transform-class-properties to have static class properties

* Upgrade Lexer and Parser files to use ES6 classes

* Update eslint max line length to 90 character (more indent because of using ES6 classes)

* Upgrade eslint and jasmin to support ES stage-2 features

* Use static properties to place constants near their functions

* Migrate all remaining sources to ES6 syntax

* Increase eslint max line length to 84

* Remove non-babelified endpoint in dev server.js

* Clean up server.js functions after removing browserified

* Make screenshotter not to use babel endpoint as we babelify everything now

src/mathMLTree.js

@@ -8,94 +8,98 @@
  * domTree.js, creating namespaced DOM nodes and HTML text markup respectively.
  */
 
-const utils = require("./utils");
+import utils from "./utils";
 
 /**
  * This node represents a general purpose MathML node of any type. The
  * constructor requires the type of node to create (for example, `"mo"` or
  * `"mspace"`, corresponding to `<mo>` and `<mspace>` tags).
  */
-function MathNode(type, children) {
-    this.type = type;
-    this.attributes = {};
-    this.children = children || [];
+class MathNode {
+    constructor(type, children) {
+        this.type = type;
+        this.attributes = {};
+        this.children = children || [];
+    }
+
+    /**
+     * Sets an attribute on a MathML node. MathML depends on attributes to convey a
+     * semantic content, so this is used heavily.
+     */
+    setAttribute(name, value) {
+        this.attributes[name] = value;
+    }
+
+    /**
+     * Converts the math node into a MathML-namespaced DOM element.
+     */
+    toNode() {
+        const node = document.createElementNS(
+            "http://www.w3.org/1998/Math/MathML", this.type);
+
+        for (const attr in this.attributes) {
+            if (Object.prototype.hasOwnProperty.call(this.attributes, attr)) {
+                node.setAttribute(attr, this.attributes[attr]);
+            }
+        }
+
+        for (let i = 0; i < this.children.length; i++) {
+            node.appendChild(this.children[i].toNode());
+        }
+
+        return node;
+    }
+
+    /**
+     * Converts the math node into an HTML markup string.
+     */
+    toMarkup() {
+        let markup = "<" + this.type;
+
+        // Add the attributes
+        for (const attr in this.attributes) {
+            if (Object.prototype.hasOwnProperty.call(this.attributes, attr)) {
+                markup += " " + attr + "=\"";
+                markup += utils.escape(this.attributes[attr]);
+                markup += "\"";
+            }
+        }
+
+        markup += ">";
+
+        for (let i = 0; i < this.children.length; i++) {
+            markup += this.children[i].toMarkup();
+        }
+
+        markup += "</" + this.type + ">";
+
+        return markup;
+    }
 }
 
-/**
- * Sets an attribute on a MathML node. MathML depends on attributes to convey a
- * semantic content, so this is used heavily.
- */
-MathNode.prototype.setAttribute = function(name, value) {
-    this.attributes[name] = value;
-};
-
-/**
- * Converts the math node into a MathML-namespaced DOM element.
- */
-MathNode.prototype.toNode = function() {
-    const node = document.createElementNS(
-        "http://www.w3.org/1998/Math/MathML", this.type);
-
-    for (const attr in this.attributes) {
-        if (Object.prototype.hasOwnProperty.call(this.attributes, attr)) {
-            node.setAttribute(attr, this.attributes[attr]);
-        }
-    }
-
-    for (let i = 0; i < this.children.length; i++) {
-        node.appendChild(this.children[i].toNode());
-    }
-
-    return node;
-};
-
-/**
- * Converts the math node into an HTML markup string.
- */
-MathNode.prototype.toMarkup = function() {
-    let markup = "<" + this.type;
-
-    // Add the attributes
-    for (const attr in this.attributes) {
-        if (Object.prototype.hasOwnProperty.call(this.attributes, attr)) {
-            markup += " " + attr + "=\"";
-            markup += utils.escape(this.attributes[attr]);
-            markup += "\"";
-        }
-    }
-
-    markup += ">";
-
-    for (let i = 0; i < this.children.length; i++) {
-        markup += this.children[i].toMarkup();
-    }
-
-    markup += "</" + this.type + ">";
-
-    return markup;
-};
-
 /**
  * This node represents a piece of text.
  */
-function TextNode(text) {
-    this.text = text;
+class TextNode {
+    constructor(text) {
+        this.text = text;
+    }
+
+    /**
+     * Converts the text node into a DOM text node.
+     */
+    toNode() {
+        return document.createTextNode(this.text);
+    }
+
+    /**
+     * Converts the text node into HTML markup (which is just the text itself).
+     */
+    toMarkup() {
+        return utils.escape(this.text);
+    }
 }
 
-/**
- * Converts the text node into a DOM text node.
- */
-TextNode.prototype.toNode = function() {
-    return document.createTextNode(this.text);
-};
-
-/**
- * Converts the text node into HTML markup (which is just the text itself).
- */
-TextNode.prototype.toMarkup = function() {
-    return utils.escape(this.text);
-};
-
 module.exports = {
     MathNode: MathNode,
     TextNode: TextNode,