Add missing files, firefox overflow / undeflow support

src/chunker/layout.js

 import { getBoundingClientRect } from "../utils/utils";
 import { walk, after, stackChildren } from "../utils/dom";
-import Parser from "./parser";
 
 /**
  * Layout
@@ -11,7 +10,6 @@ class Layout {
   constructor(element, wrapper, parser) {
     this.element = element;
     this.wrapper = wrapper;
-    this.parser = parser || new Parser();
 
     let space = this.element.getBoundingClientRect();
     this.width = Math.round(space.width);
@@ -483,11 +481,41 @@ class Layout {
     }
   }
 
+  getOverflow() {
+    let overflow = this.overflow(this.element);
+
+    if (overflow) {
+      let extracted = overflow.extractContents();
+      this._onOverflow && this._onOverflow(extracted);
+    }
+  }
+
+  getUnderflow() {
+    this._onUnderflow && this._onUnderflow();
+  }
+
   listeners() {
+    if (typeof ResizeObserver !== "undefined") {
+      this.addResizeObserver();
+    } else {
+      this.element.addEventListener("overflow", this.getOverflow.bind(this), false);
+      this.element.addEventListener("underflow", this.getUnderflow.bind(this), false);
+    }
+    // TODO: fall back to mutation observer?
+
+
+    // Key scroll width from changing
+    this.element.addEventListener("scroll", () => {
+      this.element.scrollLeft = 0;
+    });
+
+    return true;
+  }
+
+  addResizeObserver() {
     let wrapper = this.wrapper;
     let prevHeight = wrapper.getBoundingClientRect().height;
-
-    let ro = new ResizeObserver( entries => {
+    this.ro = new ResizeObserver( entries => {
       for (let entry of entries) {
         const cr = entry.contentRect;
 
@@ -514,12 +542,17 @@ class Layout {
       }
     });
 
-    ro.observe(wrapper);
+    this.ro.observe(wrapper);
+  }
 
-    // Key scroll width from changing
-    this.element.addEventListener("scroll", () => {
-      this.element.scrollLeft = 0;
-    })
+  destroy() {
+    this.element.removeEventListener("overflow", this.getOverflow.bind(this), false);
+    this.element.removeEventListener("underflow", this.getUnderflow.bind(this), false);
+
+    this.ro.disconnect();
+
+    this.element = element;
+    this.wrapper = wrapper;
   }
 
 }

src/utils/dom.js

+export function *walk(start, limiter) {
+	let node = start;
+
+	while (node) {
+
+		yield node;
+
+		if (node.childNodes.length) {
+			node = node.firstChild;
+		} else if (node.nextSibling) {
+			if (limiter && node === limiter) {
+				node = undefined;
+				break;
+			}
+			node = node.nextSibling;
+		} else {
+			while (node) {
+				node = node.parentNode;
+				if (limiter && node === limiter) {
+					node = undefined;
+					break;
+				}
+				if (node && node.nextSibling) {
+					node = node.nextSibling;
+					break;
+				}
+
+			}
+		}
+	}
+}
+
+export function after(node, limiter) {
+	let after = node;
+
+	if (after.nextSibling) {
+		if (limiter && node === limiter) {
+			return;
+		}
+		after = after.nextSibling;
+	} else {
+		while (after) {
+			after = after.parentNode;
+			if (limiter && after === limiter) {
+				after = undefined;
+				break;
+			}
+			if (after && after.nextSibling) {
+				after = after.nextSibling;
+				break;
+			}
+		}
+	}
+
+	return after;
+}
+
+export function stackChildren(currentNode, stacked) {
+	let stack = stacked || [];
+
+	stack.unshift(currentNode);
+
+	let children = currentNode.children;
+	for (var i = 0, length = children.length; i < length; i++) {
+		stackChildren(children[i], stack);
+	}
+
+	return stack;
+}

src/utils/utils.js

+export function getBoundingClientRect(element) {
+	if (!element) {
+		return;
+	}
+	let rect;
+	if (element.getBoundingClientRect) {
+		rect = element.getBoundingClientRect();
+	} else {
+		let range = document.createRange();
+		range.selectNode(element);
+		rect = range.getBoundingClientRect();
+	}
+	return rect;
+}
+
+/**
+ * Generates a UUID
+ * based on: http://stackoverflow.com/questions/105034/how-to-create-a-guid-uuid-in-javascript
+ * @returns {string} uuid
+ */
+export function UUID() {
+	var d = new Date().getTime();
+	if (typeof performance !== 'undefined' && typeof performance.now === 'function'){
+			d += performance.now(); //use high-precision timer if available
+	}
+	return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function (c) {
+			var r = (d + Math.random() * 16) % 16 | 0;
+			d = Math.floor(d / 16);
+			return (c === 'x' ? r : (r & 0x3 | 0x8)).toString(16);
+	});
+}