LibJS: Do not use the $ special character in file names

The dollar sign is a special character in POSIX shells and in the Ninja
build file format. If the file name contains a `$`, something goes wrong
in the escaping/unescaping of this symbol, and CMake/GCC/Clang generate
invalid dependency files where not all instances of `$` are escaped
properly. Because of this, Ninja fails to rebuild `$262Object.cpp` if
the headers included by it have changed.

Stale `$262Object.cpp.o` files have been the cause of mysterious crashes
multiple times which only go away after doing a clean build. Let's
prevent these from happening again by removing the `$` from the
filename.

Userland/Libraries/LibJS/CMakeLists.txt

@@ -18,7 +18,7 @@ set(SOURCES
     Bytecode/RegexTable.cpp
     Bytecode/StringTable.cpp
     Console.cpp
-    Contrib/Test262/$262Object.cpp
+    Contrib/Test262/262Object.cpp
     Contrib/Test262/AgentObject.cpp
     Contrib/Test262/GlobalObject.cpp
     Contrib/Test262/IsHTMLDDA.cpp