revert an unintended change that crept in

layout/mathml/base/src/nsMathMLFrame.cpp

@@ -217,8 +217,6 @@ nsMathMLFrame::GetAxisHeight(nsIRenderingContext& aRenderingContext,
                              nsIFontMetrics*      aFontMetrics,
                              nscoord&             aAxisHeight)
 {
-GetAxisHeight(aFontMetrics, aAxisHeight);
-return;
   // get the bounding metrics of the minus sign, the rendering context
   // is assumed to have been set with the font of the current style context
 #ifdef NS_DEBUG