[wasm] Skip Assert.InRange in Copy.cs for Browser

[mdh1418]

This PR reverts #40663.

By reverting dotnet/corefx#37583 in #40753, the file time being set

runtime/src/libraries/Native/Unix/System.Native/pal_io.c

Line 1157 in 154e971

while ((ret = futimens(outFd, origTimes)) < 0 && errno == EINTR);

is now overwritten by

runtime/src/libraries/Native/Unix/System.Native/pal_io.c

Line 1173 in 154e971

while ((ret = fchmod(outFd, sourceStat.st_mode & (S_IRWXU | S_IRWXG | S_IRWXO))) < 0 && errno == EINTR);

probably due to Emscripten's implementation. (By commenting out L1173-L1177 the test passes)

Moreover, from some testing, it looks like File.SetAttributes will overwrite a file's LastWrite and LastAccess time on browser also probably due to Emscripten's implementation.

The workaround in #40663 sets the file's LastWrite after Copy for readOnly files, but if we have to do that for both readOnly and non-readOnly because L1157 is defeated by L1173, then the Assert.InRange check is trivial and we should instead skip this assert on Browser.