Simplify length-range-check in Array.prototype.push

src/js/array.js

Index: src/js/array.js
diff --git a/src/js/array.js b/src/js/array.js
index c368cf395cee0a6327350ff89971e84719a50b7a..d4deb913942ef3773ef615d6743bc12679675361 100644
--- a/src/js/array.js
+++ b/src/js/array.js
@@ -463,14 +463,10 @@ function ArrayPush() {
   var n = TO_LENGTH(array.length);
   var m = arguments.length;
 
-  // It appears that there is no enforced, absolute limit on the number of
-  // arguments, but it would surely blow the stack to use 2**30 or more.
-  // To avoid integer overflow, do the comparison to the max safe integer
-  // after subtracting 2**30 from both sides. (2**31 would seem like a
-  // natural value, but it is negative in JS, and 2**32 is 1.)
-  if (m > (1 << 30) || (n - (1 << 30)) + m > kMaxSafeInteger - (1 << 30)) {
-    throw MakeTypeError(kPushPastSafeLength, m, n);
-  }
+  // Subtract n from kMaxSafeInteger rather than testing m + n >
+  // kMaxSafeInteger. n may already be kMaxSafeInteger. In that case adding
+  // e.g., 1 would not be safe.
+  if (m > kMaxSafeInteger - n) throw MakeTypeError(kPushPastSafeLength, m, n);
 
   for (var i = 0; i < m; i++) {
     array[i+n] = arguments[i];