back out part of this change for more testing; I missed a case which caused a crash

xpcom/ds/bufferRoutines.h

@@ -94,11 +94,20 @@ void ShiftCharsRight(char* aDest,PRUint32 aLength,PRUint32 anOffset,PRUint32 aCo
  * @param   aCount is the number of chars to be "cut"
  */
 void ShiftDoubleCharsLeft(char* aDest,PRUint32 aLength,PRUint32 anOffset,PRUint32 aCount) { 
-  PRUnichar* root=(PRUnichar*)aDest;
-  PRUnichar* dst = root+anOffset;
-  PRUnichar* src = root+anOffset+aCount;
+  //PRUint32 theMax=aLength-anOffset;
+  //PRUint32 theLength=(theMax<aCount) ? theMax : aCount;
 
-  memmove(dst,src,sizeof(PRUnichar)*(aLength-anOffset));
+  PRUnichar* theBuf=(PRUnichar*)aDest;
+  PRUnichar* first= theBuf+anOffset+aCount;
+  PRUnichar* last = theBuf+aLength;
+  PRUnichar* to   = theBuf+anOffset;
+
+  //now loop over characters, shifting them left...
+  while(first<=last) {
+    *to=*first;  
+    to++;
+    first++;
+  }
 }