--- a/layout/generic/nsBlockReflowContext.cpp
+++ b/layout/generic/nsBlockReflowContext.cpp
@@ -349,17 +349,17 @@ nsBlockReflowContext::PlaceBlock(const n
   // Compute collapsed block-end margin value.
   WritingMode wm = aReflowState.GetWritingMode();
   WritingMode parentWM = mMetrics.GetWritingMode();
   if (NS_FRAME_IS_COMPLETE(aReflowStatus)) {
     aBEndMarginResult = mMetrics.mCarriedOutBEndMargin;
     aBEndMarginResult.Include(aReflowState.ComputedLogicalMargin().
       ConvertTo(parentWM, wm).BEnd(parentWM));
   } else {
-    // The used bottom-margin is set to zero above a break.
+    // The used block-end-margin is set to zero before a break.
     aBEndMarginResult.Zero();
   }
 
   nscoord backupContainingBlockAdvance = 0;
 
   // Check whether the block's block-end margin collapses with its block-start
   // margin. See CSS 2.1 section 8.3.1; those rules seem to match
   // nsBlockFrame::IsEmpty(). Any such block must have zero block-size so
@@ -401,17 +401,17 @@ nsBlockReflowContext::PlaceBlock(const n
     // line's BEnd, and it must place the next line at a different
     // point from where this empty block will be.
     backupContainingBlockAdvance = mBStartMargin.get();
   }
 
   // See if the frame fit. If it's the first frame or empty then it
   // always fits. If the block-size is unconstrained then it always fits,
   // even if there's some sort of integer overflow that makes bCoord +
-  // mMetrics.BSize() appear to go beyond the available height.
+  // mMetrics.BSize() appear to go beyond the available block size.
   if (!empty && !aForceFit &&
       mSpace.BSize(mWritingMode) != NS_UNCONSTRAINEDSIZE) {
     nscoord bEnd = mBCoord -
                    backupContainingBlockAdvance + mMetrics.BSize(mWritingMode);
     if (bEnd > mSpace.BEnd(mWritingMode)) {
       // didn't fit, we must acquit.
       mFrame->DidReflow(mPresContext, &aReflowState,
                         nsDidReflowStatus::FINISHED);