Remove the unused $jscomp.SIMPLE_FROUND_POLYFILL define and simplify …

…the `fround` polyfill when ASSUME_ES5 is enabled.

PiperOrigin-RevId: 694276260

src/com/google/javascript/jscomp/js/es6/math/fround.js

@@ -20,7 +20,7 @@
 $jscomp.polyfill('Math.fround', function(orig) {
   if (orig) return orig;
 
-  if ($jscomp.SIMPLE_FROUND_POLYFILL || typeof Float32Array !== 'function') {
+  if (!$jscomp.ASSUME_ES5 && typeof Float32Array !== 'function') {
     // Explicitly requested a no-op polyfill, or Float32Array not available.
     return /** @return {number} */ function(/** number */ arg) {
       return arg;

src/com/google/javascript/jscomp/js/util/defines.js

@@ -36,16 +36,6 @@ $jscomp.ASSUME_NO_NATIVE_MAP = false;
  */
 $jscomp.ASSUME_NO_NATIVE_SET = false;
 
-/**
- * Whether to provide an incorrect but tiny Math.fround polyfill that just
- * returns the number given.  This is usually okay to do, particularly if
- * `Math.fround` is only used to allow the JavaScript engine to use faster
- * 32-bit float operations, but could cause problems if program logic is
- * dependent on floats being truncated consistently.
- * @define {boolean}
- */
-$jscomp.SIMPLE_FROUND_POLYFILL = false;
-
 /**
  * Whether to isolate all injected polyfills from global state. This is not
  * on by default, as it bloats code size, but is useful when code needs to