cells with width=0 become auto, added comments

content/html/content/src/nsHTMLTableCellElement.cpp

@@ -463,12 +463,18 @@ MapAttributesInto(const nsIHTMLMappedAttributes* aAttributes,
     aAttributes->GetAttribute(nsHTMLAtoms::width, widthValue);
     if (widthValue.GetUnit() == eHTMLUnit_Pixel) {     // width: pixel
       nscoord width = widthValue.GetPixelValue();
-      nscoord twips = NSIntPixelsToTwips(width, p2t);
-      pos->mWidth.SetCoordValue(twips);
+      if (width > 0) {
+        nscoord twips = NSIntPixelsToTwips(width, p2t);
+        pos->mWidth.SetCoordValue(twips);
+      }
+      // else, 0 implies AUTO for compatibility 
     }
     else if (widthValue.GetUnit() == eHTMLUnit_Percent) { // width: percent
       float widthPercent = widthValue.GetPercentValue();
-      pos->mWidth.SetPercentValue(widthPercent);
+      if (widthPercent > 0.0f) {
+        pos->mWidth.SetPercentValue(widthPercent);
+      }
+      // else, 0 implies AUTO for compatibility 
     }
 
     // height: pixel

content/html/content/src/nsHTMLTableElement.cpp

@@ -1130,7 +1130,6 @@ MapAttributesInto(const nsIHTMLMappedAttributes* aAttributes,
           break;
         }
       }
-      // else the width becomes auto if width = 0 or 0% for backward compatibility
 
       // height
       aAttributes->GetAttribute(nsHTMLAtoms::height, value);

layout/html/content/src/nsHTMLTableCellElement.cpp

@@ -463,12 +463,18 @@ MapAttributesInto(const nsIHTMLMappedAttributes* aAttributes,
     aAttributes->GetAttribute(nsHTMLAtoms::width, widthValue);
     if (widthValue.GetUnit() == eHTMLUnit_Pixel) {     // width: pixel
       nscoord width = widthValue.GetPixelValue();
-      nscoord twips = NSIntPixelsToTwips(width, p2t);
-      pos->mWidth.SetCoordValue(twips);
+      if (width > 0) {
+        nscoord twips = NSIntPixelsToTwips(width, p2t);
+        pos->mWidth.SetCoordValue(twips);
+      }
+      // else, 0 implies AUTO for compatibility 
     }
     else if (widthValue.GetUnit() == eHTMLUnit_Percent) { // width: percent
       float widthPercent = widthValue.GetPercentValue();
-      pos->mWidth.SetPercentValue(widthPercent);
+      if (widthPercent > 0.0f) {
+        pos->mWidth.SetPercentValue(widthPercent);
+      }
+      // else, 0 implies AUTO for compatibility 
     }
 
     // height: pixel

layout/html/content/src/nsHTMLTableElement.cpp

@@ -1130,7 +1130,6 @@ MapAttributesInto(const nsIHTMLMappedAttributes* aAttributes,
           break;
         }
       }
-      // else the width becomes auto if width = 0 or 0% for backward compatibility
 
       // height
       aAttributes->GetAttribute(nsHTMLAtoms::height, value);