Manually import wpt/editing and wpt/selection/

third_party/WebKit/LayoutTests/imported/wpt/selection/common.js

+"use strict";
+// TODO: iframes, contenteditable/designMode
+
+// Everything is done in functions in this test harness, so we have to declare
+// all the variables before use to make sure they can be reused.
+var selection;
+var testDiv, paras, detachedDiv, detachedPara1, detachedPara2,
+    foreignDoc, foreignPara1, foreignPara2, xmlDoc, xmlElement,
+    detachedXmlElement, detachedTextNode, foreignTextNode,
+    detachedForeignTextNode, xmlTextNode, detachedXmlTextNode,
+    processingInstruction, detachedProcessingInstruction, comment,
+    detachedComment, foreignComment, detachedForeignComment, xmlComment,
+    detachedXmlComment, docfrag, foreignDocfrag, xmlDocfrag, doctype,
+    foreignDoctype, xmlDoctype;
+var testRanges, testPoints, testNodes;
+
+function setupRangeTests() {
+    selection = getSelection();
+    testDiv = document.querySelector("#test");
+    if (testDiv) {
+        testDiv.parentNode.removeChild(testDiv);
+    }
+    testDiv = document.createElement("div");
+    testDiv.id = "test";
+    document.body.insertBefore(testDiv, document.body.firstChild);
+    // Test some diacritics, to make sure browsers are using code units here
+    // and not something like grapheme clusters.
+    testDiv.innerHTML = "<p id=a>A&#x308;b&#x308;c&#x308;d&#x308;e&#x308;f&#x308;g&#x308;h&#x308;\n"
+        + "<p id=b style=display:none>Ijklmnop\n"
+        + "<p id=c>Qrstuvwx"
+        + "<p id=d style=display:none>Yzabcdef"
+        + "<p id=e style=display:none>Ghijklmn";
+    paras = testDiv.querySelectorAll("p");
+
+    detachedDiv = document.createElement("div");
+    detachedPara1 = document.createElement("p");
+    detachedPara1.appendChild(document.createTextNode("Opqrstuv"));
+    detachedPara2 = document.createElement("p");
+    detachedPara2.appendChild(document.createTextNode("Wxyzabcd"));
+    detachedDiv.appendChild(detachedPara1);
+    detachedDiv.appendChild(detachedPara2);
+
+    // Opera doesn't automatically create a doctype for a new HTML document,
+    // contrary to spec.  It also doesn't let you add doctypes to documents
+    // after the fact through any means I've tried.  So foreignDoc in Opera
+    // will have no doctype, foreignDoctype will be null, and Opera will fail
+    // some tests somewhat mysteriously as a result.
+    foreignDoc = document.implementation.createHTMLDocument("");
+    foreignPara1 = foreignDoc.createElement("p");
+    foreignPara1.appendChild(foreignDoc.createTextNode("Efghijkl"));
+    foreignPara2 = foreignDoc.createElement("p");
+    foreignPara2.appendChild(foreignDoc.createTextNode("Mnopqrst"));
+    foreignDoc.body.appendChild(foreignPara1);
+    foreignDoc.body.appendChild(foreignPara2);
+
+    // Now we get to do really silly stuff, which nobody in the universe is
+    // ever going to actually do, but the spec defines behavior, so too bad.
+    // Testing is fun!
+    xmlDoctype = document.implementation.createDocumentType("qorflesnorf", "abcde", "x\"'y");
+    xmlDoc = document.implementation.createDocument(null, null, xmlDoctype);
+    detachedXmlElement = xmlDoc.createElement("everyone-hates-hyphenated-element-names");
+    detachedTextNode = document.createTextNode("Uvwxyzab");
+    detachedForeignTextNode = foreignDoc.createTextNode("Cdefghij");
+    detachedXmlTextNode = xmlDoc.createTextNode("Klmnopqr");
+    // PIs only exist in XML documents, so don't bother with document or
+    // foreignDoc.
+    detachedProcessingInstruction = xmlDoc.createProcessingInstruction("whippoorwill", "chirp chirp chirp");
+    detachedComment = document.createComment("Stuvwxyz");
+    // Hurrah, we finally got to "z" at the end!
+    detachedForeignComment = foreignDoc.createComment("אריה יהודה");
+    detachedXmlComment = xmlDoc.createComment("בן חיים אליעזר");
+
+    // We should also test with document fragments that actually contain stuff
+    // . . . but, maybe later.
+    docfrag = document.createDocumentFragment();
+    foreignDocfrag = foreignDoc.createDocumentFragment();
+    xmlDocfrag = xmlDoc.createDocumentFragment();
+
+    xmlElement = xmlDoc.createElement("igiveuponcreativenames");
+    xmlTextNode = xmlDoc.createTextNode("do re mi fa so la ti");
+    xmlElement.appendChild(xmlTextNode);
+    processingInstruction = xmlDoc.createProcessingInstruction("somePI", 'Did you know that ":syn sync fromstart" is very useful when using vim to edit large amounts of JavaScript embedded in HTML?');
+    xmlDoc.appendChild(xmlElement);
+    xmlDoc.appendChild(processingInstruction);
+    xmlComment = xmlDoc.createComment("I maliciously created a comment that will break incautious XML serializers, but Firefox threw an exception, so all I got was this lousy T-shirt");
+    xmlDoc.appendChild(xmlComment);
+
+    comment = document.createComment("Alphabet soup?");
+    testDiv.appendChild(comment);
+
+    foreignComment = foreignDoc.createComment('"Commenter" and "commentator" mean different things.  I\'ve seen non-native speakers trip up on this.');
+    foreignDoc.appendChild(foreignComment);
+    foreignTextNode = foreignDoc.createTextNode("I admit that I harbor doubts about whether we really need so many things to test, but it's too late to stop now.");
+    foreignDoc.body.appendChild(foreignTextNode);
+
+    doctype = document.doctype;
+    foreignDoctype = foreignDoc.doctype;
+
+    testRanges = [
+        // Various ranges within the text node children of different
+        // paragraphs.  All should be valid.
+        "[paras[0].firstChild, 0, paras[0].firstChild, 0]",
+        "[paras[0].firstChild, 0, paras[0].firstChild, 1]",
+        "[paras[0].firstChild, 2, paras[0].firstChild, 8]",
+        "[paras[0].firstChild, 2, paras[0].firstChild, 9]",
+        "[paras[1].firstChild, 0, paras[1].firstChild, 0]",
+        "[paras[1].firstChild, 0, paras[1].firstChild, 1]",
+        "[paras[1].firstChild, 2, paras[1].firstChild, 8]",
+        "[paras[1].firstChild, 2, paras[1].firstChild, 9]",
+        "[detachedPara1.firstChild, 0, detachedPara1.firstChild, 0]",
+        "[detachedPara1.firstChild, 0, detachedPara1.firstChild, 1]",
+        "[detachedPara1.firstChild, 2, detachedPara1.firstChild, 8]",
+        "[foreignPara1.firstChild, 0, foreignPara1.firstChild, 0]",
+        "[foreignPara1.firstChild, 0, foreignPara1.firstChild, 1]",
+        "[foreignPara1.firstChild, 2, foreignPara1.firstChild, 8]",
+        // Now try testing some elements, not just text nodes.
+        "[document.documentElement, 0, document.documentElement, 1]",
+        "[document.documentElement, 0, document.documentElement, 2]",
+        "[document.documentElement, 1, document.documentElement, 2]",
+        "[document.head, 1, document.head, 1]",
+        "[document.body, 0, document.body, 1]",
+        "[foreignDoc.documentElement, 0, foreignDoc.documentElement, 1]",
+        "[foreignDoc.head, 1, foreignDoc.head, 1]",
+        "[foreignDoc.body, 0, foreignDoc.body, 0]",
+        "[paras[0], 0, paras[0], 0]",
+        "[paras[0], 0, paras[0], 1]",
+        "[detachedPara1, 0, detachedPara1, 0]",
+        "[detachedPara1, 0, detachedPara1, 1]",
+        // Now try some ranges that span elements.
+        "[paras[0].firstChild, 0, paras[1].firstChild, 0]",
+        "[paras[0].firstChild, 0, paras[1].firstChild, 8]",
+        "[paras[0].firstChild, 3, paras[3], 1]",
+        // How about something that spans a node and its descendant?
+        "[paras[0], 0, paras[0].firstChild, 7]",
+        "[testDiv, 2, paras[4], 1]",
+        "[testDiv, 1, paras[2].firstChild, 5]",
+        "[document.documentElement, 1, document.body, 0]",
+        "[foreignDoc.documentElement, 1, foreignDoc.body, 0]",
+        // Then a few more interesting things just for good measure.
+        "[document, 0, document, 1]",
+        "[document, 0, document, 2]",
+        "[document, 1, document, 2]",
+        "[testDiv, 0, comment, 5]",
+        "[paras[2].firstChild, 4, comment, 2]",
+        "[paras[3], 1, comment, 8]",
+        "[foreignDoc, 0, foreignDoc, 0]",
+        "[foreignDoc, 1, foreignComment, 2]",
+        "[foreignDoc.body, 0, foreignTextNode, 36]",
+        "[xmlDoc, 0, xmlDoc, 0]",
+        // Opera 11 crashes if you extractContents() a range that ends at offset
+        // zero in a comment.  Comment out this line to run the tests successfully.
+        "[xmlDoc, 1, xmlComment, 0]",
+        "[detachedTextNode, 0, detachedTextNode, 8]",
+        "[detachedForeignTextNode, 7, detachedForeignTextNode, 7]",
+        "[detachedForeignTextNode, 0, detachedForeignTextNode, 8]",
+        "[detachedXmlTextNode, 7, detachedXmlTextNode, 7]",
+        "[detachedXmlTextNode, 0, detachedXmlTextNode, 8]",
+        "[detachedComment, 3, detachedComment, 4]",
+        "[detachedComment, 5, detachedComment, 5]",
+        "[detachedForeignComment, 0, detachedForeignComment, 1]",
+        "[detachedForeignComment, 4, detachedForeignComment, 4]",
+        "[detachedXmlComment, 2, detachedXmlComment, 6]",
+        "[docfrag, 0, docfrag, 0]",
+        "[foreignDocfrag, 0, foreignDocfrag, 0]",
+        "[xmlDocfrag, 0, xmlDocfrag, 0]",
+    ];
+
+    testPoints = [
+        // Various positions within the page, some invalid.  Remember that
+        // paras[0] is visible, and paras[1] is display: none.
+        "[paras[0].firstChild, -1]",
+        "[paras[0].firstChild, 0]",
+        "[paras[0].firstChild, 1]",
+        "[paras[0].firstChild, 2]",
+        "[paras[0].firstChild, 8]",
+        "[paras[0].firstChild, 9]",
+        "[paras[0].firstChild, 10]",
+        "[paras[0].firstChild, 65535]",
+        "[paras[1].firstChild, -1]",
+        "[paras[1].firstChild, 0]",
+        "[paras[1].firstChild, 1]",
+        "[paras[1].firstChild, 2]",
+        "[paras[1].firstChild, 8]",
+        "[paras[1].firstChild, 9]",
+        "[paras[1].firstChild, 10]",
+        "[paras[1].firstChild, 65535]",
+        "[detachedPara1.firstChild, 0]",
+        "[detachedPara1.firstChild, 1]",
+        "[detachedPara1.firstChild, 8]",
+        "[detachedPara1.firstChild, 9]",
+        "[foreignPara1.firstChild, 0]",
+        "[foreignPara1.firstChild, 1]",
+        "[foreignPara1.firstChild, 8]",
+        "[foreignPara1.firstChild, 9]",
+        // Now try testing some elements, not just text nodes.
+        "[document.documentElement, -1]",
+        "[document.documentElement, 0]",
+        "[document.documentElement, 1]",
+        "[document.documentElement, 2]",
+        "[document.documentElement, 7]",
+        "[document.head, 1]",
+        "[document.body, 3]",
+        "[foreignDoc.documentElement, 0]",
+        "[foreignDoc.documentElement, 1]",
+        "[foreignDoc.head, 0]",
+        "[foreignDoc.body, 1]",
+        "[paras[0], 0]",
+        "[paras[0], 1]",
+        "[paras[0], 2]",
+        "[paras[1], 0]",
+        "[paras[1], 1]",
+        "[paras[1], 2]",
+        "[detachedPara1, 0]",
+        "[detachedPara1, 1]",
+        "[testDiv, 0]",
+        "[testDiv, 3]",
+        // Then a few more interesting things just for good measure.
+        "[document, -1]",
+        "[document, 0]",
+        "[document, 1]",
+        "[document, 2]",
+        "[document, 3]",
+        "[comment, -1]",
+        "[comment, 0]",
+        "[comment, 4]",
+        "[comment, 96]",
+        "[foreignDoc, 0]",
+        "[foreignDoc, 1]",
+        "[foreignComment, 2]",
+        "[foreignTextNode, 0]",
+        "[foreignTextNode, 36]",
+        "[xmlDoc, -1]",
+        "[xmlDoc, 0]",
+        "[xmlDoc, 1]",
+        "[xmlDoc, 5]",
+        "[xmlComment, 0]",
+        "[xmlComment, 4]",
+        "[processingInstruction, 0]",
+        "[processingInstruction, 5]",
+        "[processingInstruction, 9]",
+        "[detachedTextNode, 0]",
+        "[detachedTextNode, 8]",
+        "[detachedForeignTextNode, 0]",
+        "[detachedForeignTextNode, 8]",
+        "[detachedXmlTextNode, 0]",
+        "[detachedXmlTextNode, 8]",
+        "[detachedProcessingInstruction, 12]",
+        "[detachedComment, 3]",
+        "[detachedComment, 5]",
+        "[detachedForeignComment, 0]",
+        "[detachedForeignComment, 4]",
+        "[detachedXmlComment, 2]",
+        "[docfrag, 0]",
+        "[foreignDocfrag, 0]",
+        "[xmlDocfrag, 0]",
+        "[doctype, 0]",
+        "[doctype, -17]",
+        "[doctype, 1]",
+        "[foreignDoctype, 0]",
+        "[xmlDoctype, 0]",
+    ];
+
+    testNodes = [
+        "paras[0]",
+        "paras[0].firstChild",
+        "paras[1]",
+        "paras[1].firstChild",
+        "foreignPara1",
+        "foreignPara1.firstChild",
+        "detachedPara1",
+        "detachedPara1.firstChild",
+        "detachedPara1",
+        "detachedPara1.firstChild",
+        "testDiv",
+        "document",
+        "detachedDiv",
+        "detachedPara2",
+        "foreignDoc",
+        "foreignPara2",
+        "xmlDoc",
+        "xmlElement",
+        "detachedXmlElement",
+        "detachedTextNode",
+        "foreignTextNode",
+        "detachedForeignTextNode",
+        "xmlTextNode",
+        "detachedXmlTextNode",
+        "processingInstruction",
+        "detachedProcessingInstruction",
+        "comment",
+        "detachedComment",
+        "foreignComment",
+        "detachedForeignComment",
+        "xmlComment",
+        "detachedXmlComment",
+        "docfrag",
+        "foreignDocfrag",
+        "xmlDocfrag",
+        "doctype",
+        "foreignDoctype",
+        "xmlDoctype",
+    ];
+}
+if ("setup" in window) {
+    setup(setupRangeTests);
+} else {
+    // Presumably we're running from within an iframe or something
+    setupRangeTests();
+}
+
+/**
+ * Return the length of a node as specified in DOM Range.
+ */
+function getNodeLength(node) {
+    if (node.nodeType == Node.DOCUMENT_TYPE_NODE) {
+        return 0;
+    }
+    if (node.nodeType == Node.TEXT_NODE || node.nodeType == Node.PROCESSING_INSTRUCTION_NODE || node.nodeType == Node.COMMENT_NODE) {
+        return node.length;
+    }
+    return node.childNodes.length;
+}
+
+/**
+ * Returns the furthest ancestor of a Node as defined by the spec.
+ */
+function furthestAncestor(node) {
+    var root = node;
+    while (root.parentNode != null) {
+        root = root.parentNode;
+    }
+    return root;
+}
+
+/**
+ * "The ancestor containers of a Node are the Node itself and all its
+ * ancestors."
+ *
+ * Is node1 an ancestor container of node2?
+ */
+function isAncestorContainer(node1, node2) {
+    return node1 == node2 ||
+        (node2.compareDocumentPosition(node1) & Node.DOCUMENT_POSITION_CONTAINS);
+}
+
+/**
+ * Returns the first Node that's after node in tree order, or null if node is
+ * the last Node.
+ */
+function nextNode(node) {
+    if (node.hasChildNodes()) {
+        return node.firstChild;
+    }
+    return nextNodeDescendants(node);
+}
+
+/**
+ * Returns the last Node that's before node in tree order, or null if node is
+ * the first Node.
+ */
+function previousNode(node) {
+    if (node.previousSibling) {
+        node = node.previousSibling;
+        while (node.hasChildNodes()) {
+            node = node.lastChild;
+        }
+        return node;
+    }
+    return node.parentNode;
+}
+
+/**
+ * Returns the next Node that's after node and all its descendants in tree
+ * order, or null if node is the last Node or an ancestor of it.
+ */
+function nextNodeDescendants(node) {
+    while (node && !node.nextSibling) {
+        node = node.parentNode;
+    }
+    if (!node) {
+        return null;
+    }
+    return node.nextSibling;
+}
+
+/**
+ * Returns the ownerDocument of the Node, or the Node itself if it's a
+ * Document.
+ */
+function ownerDocument(node) {
+    return node.nodeType == Node.DOCUMENT_NODE
+        ? node
+        : node.ownerDocument;
+}
+
+/**
+ * Returns true if ancestor is an ancestor of descendant, false otherwise.
+ */
+function isAncestor(ancestor, descendant) {
+    if (!ancestor || !descendant) {
+        return false;
+    }
+    while (descendant && descendant != ancestor) {
+        descendant = descendant.parentNode;
+    }
+    return descendant == ancestor;
+}
+
+/**
+ * Returns true if descendant is a descendant of ancestor, false otherwise.
+ */
+function isDescendant(descendant, ancestor) {
+    return isAncestor(ancestor, descendant);
+}
+
+/**
+ * The position of two boundary points relative to one another, as defined by
+ * the spec.
+ */
+function getPosition(nodeA, offsetA, nodeB, offsetB) {
+    // "If node A is the same as node B, return equal if offset A equals offset
+    // B, before if offset A is less than offset B, and after if offset A is
+    // greater than offset B."
+    if (nodeA == nodeB) {
+        if (offsetA == offsetB) {
+            return "equal";
+        }
+        if (offsetA < offsetB) {
+            return "before";
+        }
+        if (offsetA > offsetB) {
+            return "after";
+        }
+    }
+
+    // "If node A is after node B in tree order, compute the position of (node
+    // B, offset B) relative to (node A, offset A). If it is before, return
+    // after. If it is after, return before."
+    if (nodeB.compareDocumentPosition(nodeA) & Node.DOCUMENT_POSITION_FOLLOWING) {
+        var pos = getPosition(nodeB, offsetB, nodeA, offsetA);
+        if (pos == "before") {
+            return "after";
+        }
+        if (pos == "after") {
+            return "before";
+        }
+    }
+
+    // "If node A is an ancestor of node B:"
+    if (nodeB.compareDocumentPosition(nodeA) & Node.DOCUMENT_POSITION_CONTAINS) {
+        // "Let child equal node B."
+        var child = nodeB;
+
+        // "While child is not a child of node A, set child to its parent."
+        while (child.parentNode != nodeA) {
+            child = child.parentNode;
+        }
+
+        // "If the index of child is less than offset A, return after."
+        if (indexOf(child) < offsetA) {
+            return "after";
+        }
+    }
+
+    // "Return before."
+    return "before";
+}
+
+/**
+ * "contained" as defined by DOM Range: "A Node node is contained in a range
+ * range if node's furthest ancestor is the same as range's root, and (node, 0)
+ * is after range's start, and (node, length of node) is before range's end."
+ */
+function isContained(node, range) {
+    var pos1 = getPosition(node, 0, range.startContainer, range.startOffset);
+    var pos2 = getPosition(node, getNodeLength(node), range.endContainer, range.endOffset);
+
+    return furthestAncestor(node) == furthestAncestor(range.startContainer)
+        && pos1 == "after"
+        && pos2 == "before";
+}
+
+/**
+ * "partially contained" as defined by DOM Range: "A Node is partially
+ * contained in a range if it is an ancestor container of the range's start but
+ * not its end, or vice versa."
+ */
+function isPartiallyContained(node, range) {
+    var cond1 = isAncestorContainer(node, range.startContainer);
+    var cond2 = isAncestorContainer(node, range.endContainer);
+    return (cond1 && !cond2) || (cond2 && !cond1);
+}
+
+/**
+ * Index of a node as defined by the spec.
+ */
+function indexOf(node) {
+    if (!node.parentNode) {
+        // No preceding sibling nodes, right?
+        return 0;
+    }
+    var i = 0;
+    while (node != node.parentNode.childNodes[i]) {
+        i++;
+    }
+    return i;
+}
+
+/**
+ * extractContents() implementation, following the spec.  If an exception is
+ * supposed to be thrown, will return a string with the name (e.g.,
+ * "HIERARCHY_REQUEST_ERR") instead of a document fragment.  It might also
+ * return an arbitrary human-readable string if a condition is hit that implies
+ * a spec bug.
+ */
+function myExtractContents(range) {
+    // "If the context object's detached flag is set, raise an
+    // INVALID_STATE_ERR exception and abort these steps."
+    try {
+        range.collapsed;
+    } catch (e) {
+        return "INVALID_STATE_ERR";
+    }
+
+    // "Let frag be a new DocumentFragment whose ownerDocument is the same as
+    // the ownerDocument of the context object's start node."
+    var ownerDoc = range.startContainer.nodeType == Node.DOCUMENT_NODE
+        ? range.startContainer
+        : range.startContainer.ownerDocument;
+    var frag = ownerDoc.createDocumentFragment();
+
+    // "If the context object's start and end are the same, abort this method,
+    // returning frag."
+    if (range.startContainer == range.endContainer
+    && range.startOffset == range.endOffset) {
+        return frag;
+    }
+
+    // "Let original start node, original start offset, original end node, and
+    // original end offset be the context object's start and end nodes and
+    // offsets, respectively."
+    var originalStartNode = range.startContainer;
+    var originalStartOffset = range.startOffset;
+    var originalEndNode = range.endContainer;
+    var originalEndOffset = range.endOffset;
+
+    // "If original start node and original end node are the same, and they are
+    // a Text or Comment node:"
+    if (range.startContainer == range.endContainer
+    && (range.startContainer.nodeType == Node.TEXT_NODE
+    || range.startContainer.nodeType == Node.COMMENT_NODE)) {
+        // "Let clone be the result of calling cloneNode(false) on original
+        // start node."
+        var clone = originalStartNode.cloneNode(false);
+
+        // "Set the data of clone to the result of calling
+        // substringData(original start offset, original end offset − original
+        // start offset) on original start node."
+        clone.data = originalStartNode.substringData(originalStartOffset,
+            originalEndOffset - originalStartOffset);
+
+        // "Append clone as the last child of frag."
+        frag.appendChild(clone);
+
+        // "Call deleteData(original start offset, original end offset −
+        // original start offset) on original start node."
+        originalStartNode.deleteData(originalStartOffset,
+            originalEndOffset - originalStartOffset);
+
+        // "Abort this method, returning frag."
+        return frag;
+    }
+
+    // "Let common ancestor equal original start node."
+    var commonAncestor = originalStartNode;
+
+    // "While common ancestor is not an ancestor container of original end
+    // node, set common ancestor to its own parent."
+    while (!isAncestorContainer(commonAncestor, originalEndNode)) {
+        commonAncestor = commonAncestor.parentNode;
+    }
+
+    // "If original start node is an ancestor container of original end node,
+    // let first partially contained child be null."
+    var firstPartiallyContainedChild;
+    if (isAncestorContainer(originalStartNode, originalEndNode)) {
+        firstPartiallyContainedChild = null;
+    // "Otherwise, let first partially contained child be the first child of
+    // common ancestor that is partially contained in the context object."
+    } else {
+        for (var i = 0; i < commonAncestor.childNodes.length; i++) {
+            if (isPartiallyContained(commonAncestor.childNodes[i], range)) {
+                firstPartiallyContainedChild = commonAncestor.childNodes[i];
+                break;
+            }
+        }
+        if (!firstPartiallyContainedChild) {
+            throw "Spec bug: no first partially contained child!";
+        }
+    }
+
+    // "If original end node is an ancestor container of original start node,
+    // let last partially contained child be null."
+    var lastPartiallyContainedChild;
+    if (isAncestorContainer(originalEndNode, originalStartNode)) {
+        lastPartiallyContainedChild = null;
+    // "Otherwise, let last partially contained child be the last child of
+    // common ancestor that is partially contained in the context object."
+    } else {
+        for (var i = commonAncestor.childNodes.length - 1; i >= 0; i--) {
+            if (isPartiallyContained(commonAncestor.childNodes[i], range)) {
+                lastPartiallyContainedChild = commonAncestor.childNodes[i];
+                break;
+            }
+        }
+        if (!lastPartiallyContainedChild) {
+            throw "Spec bug: no last partially contained child!";
+        }
+    }
+
+    // "Let contained children be a list of all children of common ancestor
+    // that are contained in the context object, in tree order."
+    //
+    // "If any member of contained children is a DocumentType, raise a
+    // HIERARCHY_REQUEST_ERR exception and abort these steps."
+    var containedChildren = [];
+    for (var i = 0; i < commonAncestor.childNodes.length; i++) {
+        if (isContained(commonAncestor.childNodes[i], range)) {
+            if (commonAncestor.childNodes[i].nodeType
+            == Node.DOCUMENT_TYPE_NODE) {
+                return "HIERARCHY_REQUEST_ERR";
+            }
+            containedChildren.push(commonAncestor.childNodes[i]);
+        }
+    }
+
+    // "If original start node is an ancestor container of original end node,
+    // set new node to original start node and new offset to original start
+    // offset."
+    var newNode, newOffset;
+    if (isAncestorContainer(originalStartNode, originalEndNode)) {
+        newNode = originalStartNode;
+        newOffset = originalStartOffset;
+    // "Otherwise:"
+    } else {
+        // "Let reference node equal original start node."
+        var referenceNode = originalStartNode;
+
+        // "While reference node's parent is not null and is not an ancestor
+        // container of original end node, set reference node to its parent."
+        while (referenceNode.parentNode
+        && !isAncestorContainer(referenceNode.parentNode, originalEndNode)) {
+            referenceNode = referenceNode.parentNode;
+        }
+
+        // "Set new node to the parent of reference node, and new offset to one
+        // plus the index of reference node."
+        newNode = referenceNode.parentNode;
+        newOffset = 1 + indexOf(referenceNode);
+    }
+
+    // "If first partially contained child is a Text or Comment node:"
+    if (firstPartiallyContainedChild
+    && (firstPartiallyContainedChild.nodeType == Node.TEXT_NODE
+    || firstPartiallyContainedChild.nodeType == Node.COMMENT_NODE)) {
+        // "Let clone be the result of calling cloneNode(false) on original
+        // start node."
+        var clone = originalStartNode.cloneNode(false);
+
+        // "Set the data of clone to the result of calling substringData() on
+        // original start node, with original start offset as the first
+        // argument and (length of original start node − original start offset)
+        // as the second."
+        clone.data = originalStartNode.substringData(originalStartOffset,
+            getNodeLength(originalStartNode) - originalStartOffset);
+
+        // "Append clone as the last child of frag."
+        frag.appendChild(clone);
+
+        // "Call deleteData() on original start node, with original start
+        // offset as the first argument and (length of original start node −
+        // original start offset) as the second."
+        originalStartNode.deleteData(originalStartOffset,
+            getNodeLength(originalStartNode) - originalStartOffset);
+    // "Otherwise, if first partially contained child is not null:"
+    } else if (firstPartiallyContainedChild) {
+        // "Let clone be the result of calling cloneNode(false) on first
+        // partially contained child."
+        var clone = firstPartiallyContainedChild.cloneNode(false);
+
+        // "Append clone as the last child of frag."
+        frag.appendChild(clone);
+
+        // "Let subrange be a new Range whose start is (original start node,
+        // original start offset) and whose end is (first partially contained
+        // child, length of first partially contained child)."
+        var subrange = ownerDoc.createRange();
+        subrange.setStart(originalStartNode, originalStartOffset);
+        subrange.setEnd(firstPartiallyContainedChild,
+            getNodeLength(firstPartiallyContainedChild));
+
+        // "Let subfrag be the result of calling extractContents() on
+        // subrange."
+        var subfrag = myExtractContents(subrange);
+
+        // "For each child of subfrag, in order, append that child to clone as
+        // its last child."
+        for (var i = 0; i < subfrag.childNodes.length; i++) {
+            clone.appendChild(subfrag.childNodes[i]);
+        }
+    }
+
+    // "For each contained child in contained children, append contained child
+    // as the last child of frag."
+    for (var i = 0; i < containedChildren.length; i++) {
+        frag.appendChild(containedChildren[i]);
+    }
+
+    // "If last partially contained child is a Text or Comment node:"
+    if (lastPartiallyContainedChild
+    && (lastPartiallyContainedChild.nodeType == Node.TEXT_NODE
+    || lastPartiallyContainedChild.nodeType == Node.COMMENT_NODE)) {
+        // "Let clone be the result of calling cloneNode(false) on original
+        // end node."
+        var clone = originalEndNode.cloneNode(false);
+
+        // "Set the data of clone to the result of calling substringData(0,
+        // original end offset) on original end node."
+        clone.data = originalEndNode.substringData(0, originalEndOffset);
+
+        // "Append clone as the last child of frag."
+        frag.appendChild(clone);
+
+        // "Call deleteData(0, original end offset) on original end node."
+        originalEndNode.deleteData(0, originalEndOffset);
+    // "Otherwise, if last partially contained child is not null:"
+    } else if (lastPartiallyContainedChild) {
+        // "Let clone be the result of calling cloneNode(false) on last
+        // partially contained child."
+        var clone = lastPartiallyContainedChild.cloneNode(false);
+
+        // "Append clone as the last child of frag."
+        frag.appendChild(clone);
+
+        // "Let subrange be a new Range whose start is (last partially
+        // contained child, 0) and whose end is (original end node, original
+        // end offset)."
+        var subrange = ownerDoc.createRange();
+        subrange.setStart(lastPartiallyContainedChild, 0);
+        subrange.setEnd(originalEndNode, originalEndOffset);
+
+        // "Let subfrag be the result of calling extractContents() on
+        // subrange."
+        var subfrag = myExtractContents(subrange);
+
+        // "For each child of subfrag, in order, append that child to clone as
+        // its last child."
+        for (var i = 0; i < subfrag.childNodes.length; i++) {
+            clone.appendChild(subfrag.childNodes[i]);
+        }
+    }
+
+    // "Set the context object's start and end to (new node, new offset)."
+    range.setStart(newNode, newOffset);
+    range.setEnd(newNode, newOffset);
+
+    // "Return frag."
+    return frag;
+}
+
+/**
+ * insertNode() implementation, following the spec.  If an exception is
+ * supposed to be thrown, will return a string with the name (e.g.,
+ * "HIERARCHY_REQUEST_ERR") instead of a document fragment.  It might also
+ * return an arbitrary human-readable string if a condition is hit that implies
+ * a spec bug.
+ */
+function myInsertNode(range, newNode) {
+    // "If the context object's detached flag is set, raise an
+    // INVALID_STATE_ERR exception and abort these steps."
+    //
+    // Assume that if accessing collapsed throws, it's detached.
+    try {
+        range.collapsed;
+    } catch (e) {
+        return "INVALID_STATE_ERR";
+    }
+
+    // "If the context object's start node is a Text or Comment node and its
+    // parent is null, raise an HIERARCHY_REQUEST_ERR exception and abort these
+    // steps."
+    if ((range.startContainer.nodeType == Node.TEXT_NODE
+    || range.startContainer.nodeType == Node.COMMENT_NODE)
+    && !range.startContainer.parentNode) {
+        return "HIERARCHY_REQUEST_ERR";
+    }
+
+    // "If the context object's start node is a Text node, run splitText() on
+    // it with the context object's start offset as its argument, and let
+    // reference node be the result."
+    var referenceNode;
+    if (range.startContainer.nodeType == Node.TEXT_NODE) {
+        // We aren't testing how ranges vary under mutations, and browsers vary
+        // in how they mutate for splitText, so let's just force the correct
+        // way.
+        var start = [range.startContainer, range.startOffset];
+        var end = [range.endContainer, range.endOffset];
+
+        referenceNode = range.startContainer.splitText(range.startOffset);
+
+        if (start[0] == end[0]
+        && end[1] > start[1]) {
+            end[0] = referenceNode;
+            end[1] -= start[1];
+        } else if (end[0] == start[0].parentNode
+        && end[1] > indexOf(referenceNode)) {
+            end[1]++;
+        }
+        range.setStart(start[0], start[1]);
+        range.setEnd(end[0], end[1]);
+    // "Otherwise, if the context object's start node is a Comment, let
+    // reference node be the context object's start node."
+    } else if (range.startContainer.nodeType == Node.COMMENT_NODE) {
+        referenceNode = range.startContainer;
+    // "Otherwise, let reference node be the child of the context object's
+    // start node with index equal to the context object's start offset, or
+    // null if there is no such child."
+    } else {
+        referenceNode = range.startContainer.childNodes[range.startOffset];
+        if (typeof referenceNode == "undefined") {
+            referenceNode = null;
+        }
+    }
+
+    // "If reference node is null, let parent node be the context object's
+    // start node."
+    var parentNode;
+    if (!referenceNode) {
+        parentNode = range.startContainer;
+    // "Otherwise, let parent node be the parent of reference node."
+    } else {
+        parentNode = referenceNode.parentNode;
+    }
+
+    // "Call insertBefore(newNode, reference node) on parent node, re-raising
+    // any exceptions that call raised."
+    try {
+        parentNode.insertBefore(newNode, referenceNode);
+    } catch (e) {
+        return getDomExceptionName(e);
+    }
+}
+
+/**
+ * Asserts that two nodes are equal, in the sense of isEqualNode().  If they
+ * aren't, tries to print a relatively informative reason why not.  TODO: Move
+ * this to testharness.js?
+ */
+function assertNodesEqual(actual, expected, msg) {
+    if (!actual.isEqualNode(expected)) {
+        msg = "Actual and expected mismatch for " + msg + ".  ";
+
+        while (actual && expected) {
+            assert_true(actual.nodeType === expected.nodeType
+                && actual.nodeName === expected.nodeName
+                && actual.nodeValue === expected.nodeValue
+                && actual.childNodes.length === expected.childNodes.length,
+                "First differing node: expected " + format_value(expected)
+                + ", got " + format_value(actual));
+            actual = nextNode(actual);
+            expected = nextNode(expected);
+        }
+
+        assert_unreached("DOMs were not equal but we couldn't figure out why");
+    }
+}
+
+/**
+ * Given a DOMException, return the name (e.g., "HIERARCHY_REQUEST_ERR").  In
+ * theory this should be just e.name, but in practice it's not.  So I could
+ * legitimately just return e.name, but then every engine but WebKit would fail
+ * every test, since no one seems to care much for standardizing DOMExceptions.
+ * Instead I mangle it to account for browser bugs, so as not to fail
+ * insertNode() tests (for instance) for insertBefore() bugs.  Of course, a
+ * standards-compliant browser will work right in any event.
+ *
+ * If the exception has no string property called "name" or "message", we just
+ * re-throw it.
+ */
+function getDomExceptionName(e) {
+    if (typeof e.name == "string"
+    && /^[A-Z_]+_ERR$/.test(e.name)) {
+        // Either following the standard, or prefixing NS_ERROR_DOM (I'm
+        // looking at you, Gecko).
+        return e.name.replace(/^NS_ERROR_DOM_/, "");
+    }
+
+    if (typeof e.message == "string"
+    && /^[A-Z_]+_ERR$/.test(e.message)) {
+        // Opera
+        return e.message;
+    }
+
+    if (typeof e.message == "string"
+    && /^DOM Exception:/.test(e.message)) {
+        // IE
+        return /[A-Z_]+_ERR/.exec(e.message)[0];
+    }
+
+    throw e;
+}
+
+/**
+ * Given an array of endpoint data [start container, start offset, end
+ * container, end offset], returns a Range with those endpoints.
+ */
+function rangeFromEndpoints(endpoints) {
+    // If we just use document instead of the ownerDocument of endpoints[0],
+    // WebKit will throw on setStart/setEnd.  This is a WebKit bug, but it's in
+    // range, not selection, so we don't want to fail anything for it.
+    var range = ownerDocument(endpoints[0]).createRange();
+    range.setStart(endpoints[0], endpoints[1]);
+    range.setEnd(endpoints[2], endpoints[3]);
+    return range;
+}
+
+/**
+ * Given an array of endpoint data [start container, start offset, end
+ * container, end offset], sets the selection to have those endpoints.  Uses
+ * addRange, so the range will be forwards.  Accepts an empty array for
+ * endpoints, in which case the selection will just be emptied.
+ */
+function setSelectionForwards(endpoints) {
+    selection.removeAllRanges();
+    if (endpoints.length) {
+        selection.addRange(rangeFromEndpoints(endpoints));
+    }
+}
+
+/**
+ * Given an array of endpoint data [start container, start offset, end
+ * container, end offset], sets the selection to have those endpoints, with the
+ * direction backwards.  Uses extend, so it will throw in IE.  Accepts an empty
+ * array for endpoints, in which case the selection will just be emptied.
+ */
+function setSelectionBackwards(endpoints) {
+    selection.removeAllRanges();
+    if (endpoints.length) {
+        selection.collapse(endpoints[2], endpoints[3]);
+        selection.extend(endpoints[0], endpoints[1]);
+    }
+}