buffer: use faster integer argument check

PR-URL: #54089
Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Daniel Lemire <daniel@lemire.me>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>

Author: ronag

lib/buffer.js

@@ -28,6 +28,7 @@ const {
  MathFloor,
  MathMin,
  MathTrunc,
+ NumberIsInteger,
  NumberIsNaN,
  NumberMAX_SAFE_INTEGER,
  NumberMIN_SAFE_INTEGER,
@@ -208,23 +209,23 @@ function _copy(source, target, targetStart, sourceStart, sourceEnd) {
 if(targetStart===undefined){
 targetStart=0;
 }else{
-targetStart=toInteger(targetStart,0);
+targetStart=NumberIsInteger(targetStart) ? targetStart : toInteger(targetStart,0);
 if(targetStart<0)
 thrownewERR_OUT_OF_RANGE('targetStart','>= 0',targetStart);
 }
 
 if(sourceStart===undefined){
 sourceStart=0;
 }else{
-sourceStart=toInteger(sourceStart,0);
+sourceStart=NumberIsInteger(sourceStart) ? sourceStart : toInteger(sourceStart,0);
 if(sourceStart<0||sourceStart>source.length)
 thrownewERR_OUT_OF_RANGE('sourceStart',`>= 0 && <= ${source.length}`,sourceStart);
 }
 
 if(sourceEnd===undefined){
 sourceEnd=source.length;
 }else{
-sourceEnd=toInteger(sourceEnd,0);
+sourceEnd=NumberIsInteger(sourceEnd) ? sourceEnd : toInteger(sourceEnd,0);
 if(sourceEnd<0)
 thrownewERR_OUT_OF_RANGE('sourceEnd','>= 0',sourceEnd);
 }