Regression for "WebGL build is missing "malloc" and "free" functions when passing "-sERROR_ON_UNDEFINED_SYMBOLS=0" to emscriptenArgs"

This bug regressed: [Internal link]
The fix is missing in emscripten in Unity 6.1-6.5.

Reproduction steps:

1. Open the attached “WebGLMissingMethodRepro.zip” project
2. Open the “SampleScene” scene (Assets > Scenes)
3. Build and Run for the WebGL (File > Build and Run)
4. Observe the Player in the browser and turn on Developer Tools (press F12)
   Expected result: No errors are thrown
   Actual result: “missing function: malloc” and “missing function: free” errors are thrown in the browser’s Console

Reproducible with versions: 6000.0.58f1, 6000.1.0a2, 6000.2.0a1, 6000.3.0a1, 6000.4.0a1, 6000.5.0a1
Not reproducible with versions:  6000.0.11f1, 6000.1.0a1

Tested on (OS): MacOS 15.7.1

Notes:

•  This PR needs to be ported to Emscripten 3.1.38.4-unity: https://github.com/Unity-Technologies/emscripten/pull/10 (missing in all branches after 3.1.38.1-unity)