--- a/layout/style/nsCSSDeclaration.cpp
+++ b/layout/style/nsCSSDeclaration.cpp
@@ -484,19 +484,17 @@ nsCSSDeclaration::AppendCSSValueToString
     case eCSSUnit_Meter:        aResult.AppendLiteral("m");    break;
     case eCSSUnit_Kilometer:    aResult.AppendLiteral("km");   break;
     case eCSSUnit_Point:        aResult.AppendLiteral("pt");   break;
     case eCSSUnit_Pica:         aResult.AppendLiteral("pc");   break;
     case eCSSUnit_Didot:        aResult.AppendLiteral("dt");   break;
     case eCSSUnit_Cicero:       aResult.AppendLiteral("cc");   break;
 
     case eCSSUnit_EM:           aResult.AppendLiteral("em");   break;
-    case eCSSUnit_EN:           aResult.AppendLiteral("en");   break;
     case eCSSUnit_XHeight:      aResult.AppendLiteral("ex");   break;
-    case eCSSUnit_CapHeight:    aResult.AppendLiteral("cap");  break;
     case eCSSUnit_Char:         aResult.AppendLiteral("ch");   break;
 
     case eCSSUnit_Pixel:        aResult.AppendLiteral("px");   break;
 
     case eCSSUnit_Degree:       aResult.AppendLiteral("deg");  break;
     case eCSSUnit_Grad:         aResult.AppendLiteral("grad"); break;
     case eCSSUnit_Radian:       aResult.AppendLiteral("rad");  break;
 

--- a/layout/style/nsCSSValue.h
+++ b/layout/style/nsCSSValue.h
@@ -134,20 +134,18 @@ enum nsCSSUnit {
 
   // European Typographic
   eCSSUnit_Didot        = 400,    // (float) 15 didots == 16 points
   eCSSUnit_Cicero       = 401,    // (float) 12 didots
 
   // Length units - relative
   // Font relative measure
   eCSSUnit_EM           = 800,    // (float) == current font size
-  eCSSUnit_EN           = 801,    // (float) .5 em
-  eCSSUnit_XHeight      = 802,    // (float) distance from top of lower case x to baseline
-  eCSSUnit_CapHeight    = 803,    // (float) distance from top of uppercase case H to baseline
-  eCSSUnit_Char         = 804,    // (float) number of characters, used for width with monospace font
+  eCSSUnit_XHeight      = 801,    // (float) distance from top of lower case x to baseline
+  eCSSUnit_Char         = 802,    // (float) number of characters, used for width with monospace font
 
   // Screen relative measure
   eCSSUnit_Pixel        = 900,    // (float) CSS pixel unit
 
   // Angular units
   eCSSUnit_Degree       = 1000,    // (float) 360 per circle
   eCSSUnit_Grad         = 1001,    // (float) 400 per circle
   eCSSUnit_Radian       = 1002,    // (float) 2*pi per circle

--- a/layout/style/nsRuleNode.cpp
+++ b/layout/style/nsRuleNode.cpp
@@ -193,32 +193,24 @@ static nscoord CalcLengthWith(const nsCS
     // prefs into account?
     aFontSize = aStyleFont->mFont.size;
   }
   switch (unit) {
     case eCSSUnit_EM: {
       return NSToCoordRoundWithClamp(aValue.GetFloatValue() * float(aFontSize));
       // XXX scale against font metrics height instead?
     }
-    case eCSSUnit_EN: {
-      return NSToCoordRoundWithClamp((aValue.GetFloatValue() * float(aFontSize)) / 2.0f);
-    }
     case eCSSUnit_XHeight: {
       nsFont font = aStyleFont->mFont;
       font.size = aFontSize;
       nsCOMPtr<nsIFontMetrics> fm = aPresContext->GetMetricsFor(font);
       nscoord xHeight;
       fm->GetXHeight(xHeight);
       return NSToCoordRoundWithClamp(aValue.GetFloatValue() * float(xHeight));
     }
-    case eCSSUnit_CapHeight: {
-      NS_NOTYETIMPLEMENTED("cap height unit");
-      nscoord capHeight = ((aFontSize / 3) * 2); // XXX HACK!
-      return NSToCoordRoundWithClamp(aValue.GetFloatValue() * float(capHeight));
-    }
     case eCSSUnit_Char: {
       nsFont font = aStyleFont->mFont;
       font.size = aFontSize;
       nsCOMPtr<nsIFontMetrics> fm = aPresContext->GetMetricsFor(font);
       nsCOMPtr<nsIThebesFontMetrics> tfm(do_QueryInterface(fm));
       gfxFloat zeroWidth = (tfm->GetThebesFontGroup()->GetFontAt(0)
                             ->GetMetrics().zeroOrAveCharWidth);