perf(core): resolve O(N^2) memory reallocation bottleneck in line-break tokenization (#2434)

* perf(core): eliminate O(N^2) memory reallocation in split_linebreaks

* feat(core): optimize split_linebreaks and fix CI Node version

* Update package-lock.json

---------

Co-authored-by: Mounesh <work.mounesh@example.com>
Co-authored-by: Liam Newman <bitwiseman@gmail.com>

Author: 3 people

js/src/javascript/beautifier.js

@@ -104,15 +104,16 @@ function split_linebreaks(s) {
   //return s.split(/\x0d\x0a|\x0a/);
 
   s = s.replace(acorn.allLineBreaks, '\n');
-  var out = [],
-    idx = s.indexOf("\n");
+  var out = [];
+  var start = 0;
+  var idx = s.indexOf("\n", start);
   while (idx !== -1) {
-    out.push(s.substring(0, idx));
-    s = s.substring(idx + 1);
-    idx = s.indexOf("\n");
+    out.push(s.substring(start, idx));
+    start = idx + 1;
+    idx = s.indexOf("\n", start);
   }
-  if (s.length) {
-    out.push(s);
+  if (start < s.length) {
+    out.push(s.substring(start));
   }
   return out;
 }