LibJS/Bytecode: Move environment variable caches into instructions

These were out-of-line because we had some ideas about marking
instruction streams PROT_READ only, but that seems pretty arbitrary and
there's a lot of performance to be gained by putting these inline.

Userland/Libraries/LibJS/Bytecode/Executable.cpp

@@ -23,7 +23,6 @@ Executable::Executable(
     NonnullRefPtr<SourceCode const> source_code,
     size_t number_of_property_lookup_caches,
     size_t number_of_global_variable_caches,
-    size_t number_of_environment_variable_caches,
     size_t number_of_registers,
     bool is_strict_mode)
     : bytecode(move(bytecode))
@@ -37,7 +36,6 @@ Executable::Executable(
 {
     property_lookup_caches.resize(number_of_property_lookup_caches);
     global_variable_caches.resize(number_of_global_variable_caches);
-    environment_variable_caches.resize(number_of_environment_variable_caches);
 }
 
 Executable::~Executable() = default;