Editorial: flip non-null/otherwise conditions

PR: #234

dom.bs

@@ -2517,9 +2517,8 @@ invoked, must run these steps:
  <li><p>Let <var>node</var> be the result of <a>converting nodes into a node</a>, given
  <var>nodes</var> and <a>context object</a>'s <a>node document</a>. Rethrow any exceptions.
 
- <li><p>If <var>viablePreviousSibling</var> is non-null, set it to
- <var>viablePreviousSibling</var>'s <a>next sibling</a>, and to <var>parent</var>'s
- <a>first child</a> otherwise.
+ <li><p>If <var>viablePreviousSibling</var> is null, set it to <var>parent</var>'s
+ <a>first child</a>, and to <var>viablePreviousSibling</var>'s <a>next sibling</a> otherwise.
 
  <li><p><a>Pre-insert</a> <var>node</var> into <var>parent</var> before
  <var>viablePreviousSibling</var>. Rethrow any exceptions.
@@ -8719,11 +8718,10 @@ The <dfn><code>NodeIterator</code> pre-removing steps</dfn> given a
     <p class="note no-backref">Steps are not terminated here.
   </ol>
 
- <li><p>Set <var>nodeIterator</var>'s {{NodeIterator/referenceNode}} attribute to the
- <a>inclusive descendant</a> of <var>toBeRemovedNode</var>'s <a>previous sibling</a> that
- appears last in <a>tree order</a>, if <var>toBeRemovedNode</var>'s
- <a>previous sibling</a> is non-null, and to <var>toBeRemovedNode</var>'s <a>parent</a>
- otherwise.
+ <li><p>Set <var>nodeIterator</var>'s {{NodeIterator/referenceNode}} attribute to
+ <var>toBeRemovedNode</var>'s <a>parent</a>, if <var>toBeRemovedNode</var>'s <a>previous sibling</a>
+ is null, and to the <a>inclusive descendant</a> of <var>toBeRemovedNode</var>'s
+ <a>previous sibling</a> that appears last in <a>tree order</a> otherwise.
 </ol>
 
 <hr>
@@ -9714,6 +9712,7 @@ making this standard what it is today.
 With that, many thanks to
 Adam Klein,
 Adrian Bateman,
+Aleksey Shvayka,
 Alex Komoroske,
 Alex Russell,
 Anthony Ramine,

dom.html

@@ -71,7 +71,7 @@
    <p data-fill-with="logo"><a class="logo" href="https://whatwg.org/"> <img alt="WHATWG" height="100" src="https://resources.whatwg.org/logo-dom.svg"> </a> </p>
    <hgroup>
     <h1 class="p-name no-ref allcaps" id="title">DOM</h1>
-    <h2 class="no-num no-toc no-ref heading settled" id="subtitle"><span class="content">Living Standard — Last Updated <time class="dt-updated" datetime="2016-04-20">20 April 2016</time></span></h2>
+    <h2 class="no-num no-toc no-ref heading settled" id="subtitle"><span class="content">Living Standard — Last Updated <time class="dt-updated" datetime="2016-04-21">21 April 2016</time></span></h2>
    </hgroup>
    <div data-fill-with="spec-metadata">
     <dl>
@@ -1594,7 +1594,7 @@ <h4 class="heading settled" data-level="4.2.8" id="interface-childnode"><span cl
     <li>
      <p>Let <var>node</var> be the result of <a data-link-type="dfn" href="#converting-nodes-into-a-node">converting nodes into a node</a>, given <var>nodes</var> and <a data-link-type="dfn" href="#context-object">context object</a>’s <a data-link-type="dfn" href="#concept-node-document">node document</a>. Rethrow any exceptions. </p>
     <li>
-     <p>If <var>viablePreviousSibling</var> is non-null, set it to <var>viablePreviousSibling</var>’s <a data-link-type="dfn" href="#concept-tree-next-sibling">next sibling</a>, and to <var>parent</var>’s <a data-link-type="dfn" href="#concept-tree-first-child">first child</a> otherwise. </p>
+     <p>If <var>viablePreviousSibling</var> is null, set it to <var>parent</var>’s <a data-link-type="dfn" href="#concept-tree-first-child">first child</a>, and to <var>viablePreviousSibling</var>’s <a data-link-type="dfn" href="#concept-tree-next-sibling">next sibling</a> otherwise. </p>
     <li>
      <p><a data-link-type="dfn" href="#concept-node-pre-insert">Pre-insert</a> <var>node</var> into <var>parent</var> before <var>viablePreviousSibling</var>. Rethrow any exceptions. </p>
    </ol>
@@ -4621,8 +4621,7 @@ <h3 class="heading settled" data-level="6.1" id="interface-nodeiterator"><span c
        <p class="note no-backref" role="note">Steps are not terminated here. </p>
      </ol>
     <li>
-     <p>Set <var>nodeIterator</var>’s <code class="idl"><a data-link-type="idl" href="#dom-nodeiterator-referencenode">referenceNode</a></code> attribute to the <a data-link-type="dfn" href="#concept-tree-inclusive-descendant">inclusive descendant</a> of <var>toBeRemovedNode</var>’s <a data-link-type="dfn" href="#concept-tree-previous-sibling">previous sibling</a> that
- appears last in <a data-link-type="dfn" href="#concept-tree-order">tree order</a>, if <var>toBeRemovedNode</var>’s <a data-link-type="dfn" href="#concept-tree-previous-sibling">previous sibling</a> is non-null, and to <var>toBeRemovedNode</var>’s <a data-link-type="dfn" href="#concept-tree-parent">parent</a> otherwise. </p>
+     <p>Set <var>nodeIterator</var>’s <code class="idl"><a data-link-type="idl" href="#dom-nodeiterator-referencenode">referenceNode</a></code> attribute to <var>toBeRemovedNode</var>’s <a data-link-type="dfn" href="#concept-tree-parent">parent</a>, if <var>toBeRemovedNode</var>’s <a data-link-type="dfn" href="#concept-tree-previous-sibling">previous sibling</a> is null, and to the <a data-link-type="dfn" href="#concept-tree-inclusive-descendant">inclusive descendant</a> of <var>toBeRemovedNode</var>’s <a data-link-type="dfn" href="#concept-tree-previous-sibling">previous sibling</a> that appears last in <a data-link-type="dfn" href="#concept-tree-order">tree order</a> otherwise. </p>
    </ol>
    <hr>
    <p>The <dfn class="idl-code" data-dfn-for="NodeIterator" data-dfn-type="attribute" data-export="" id="dom-nodeiterator-root">root<a class="self-link" href="#dom-nodeiterator-root"></a></dfn> attribute
@@ -5198,6 +5197,7 @@ <h2 class="no-num heading settled" id="acks"><span class="content">Acknowledgmen
    <p>With that, many thanks to
 Adam Klein,
 Adrian Bateman,
+Aleksey Shvayka,
 Alex Komoroske,
 Alex Russell,
 Anthony Ramine,