Bug 1584170: part 1) Factor out duplicated code to `IsInOlOrUl`. r=hsivonen

Differential Revision: https://phabricator.services.mozilla.com/D48320

--HG--
extra : moz-landing-system : lando

dom/base/nsPlainTextSerializer.cpp

@@ -743,12 +743,12 @@ nsresult nsPlainTextSerializer::DoOpenContainer(const nsAtom* aTag) {
     }
   } else if (aTag == nsGkAtoms::ul) {
     // Indent here to support nested lists, which aren't included in li :-(
-    EnsureVerticalSpace(mULCount + mOLStackIndex == 0 ? 1 : 0);
+    EnsureVerticalSpace(IsInOlOrUl() ? 0 : 1);
     // Must end the current line before we change indention
     mCurrentLine.mIndentation.mLength += kIndentSizeList;
     mULCount++;
   } else if (aTag == nsGkAtoms::ol) {
-    EnsureVerticalSpace(mULCount + mOLStackIndex == 0 ? 1 : 0);
+    EnsureVerticalSpace(IsInOlOrUl() ? 0 : 1);
     if (mSettings.HasFlag(nsIDocumentEncoder::OutputFormatted)) {
       // Must end the current line before we change indention
       if (mOLStackIndex < OLStackSize) {
@@ -974,7 +974,8 @@ nsresult nsPlainTextSerializer::DoCloseContainer(const nsAtom* aTag) {
   } else if (aTag == nsGkAtoms::ul) {
     mOutputManager->Flush(mCurrentLine);
     mCurrentLine.mIndentation.mLength -= kIndentSizeList;
-    if (--mULCount + mOLStackIndex == 0) {
+    --mULCount;
+    if (!IsInOlOrUl()) {
       mFloatingLines = 1;
       mLineBreakDue = true;
     }
@@ -984,7 +985,7 @@ nsresult nsPlainTextSerializer::DoCloseContainer(const nsAtom* aTag) {
     mCurrentLine.mIndentation.mLength -= kIndentSizeList;
     NS_ASSERTION(mOLStackIndex, "Wrong OLStack level!");
     mOLStackIndex--;
-    if (mULCount + mOLStackIndex == 0) {
+    if (!IsInOlOrUl()) {
       mFloatingLines = 1;
       mLineBreakDue = true;
     }
@@ -1765,6 +1766,10 @@ bool nsPlainTextSerializer::IsInOL() const {
   return false;
 }
 
+bool nsPlainTextSerializer::IsInOlOrUl() const {
+  return (mULCount > 0) || (mOLStackIndex > 0);
+}
+
 /*
   @return 0 = no header, 1 = h1, ..., 6 = h6
 */

dom/base/nsPlainTextSerializer.h

@@ -106,6 +106,7 @@ class nsPlainTextSerializer final : public nsIContentSerializer {
   //         element.
   bool IsElementPreformatted() const;
   bool IsInOL() const;
+  bool IsInOlOrUl() const;
   bool IsCurrentNodeConverted() const;
   bool MustSuppressLeaf() const;