LibJS: Lazily collect stack trace information

The previous implementation was calling `backtrace()` for every
function call, which is quite slow.

Instead, this implementation provides VM::stack_trace() which unwinds
the native stack, maps it through NativeExecutable::get_source_range
and combines it with source ranges from interpreted call frames.

Meta/gn/secondary/Userland/Libraries/LibJS/BUILD.gn

@@ -6,6 +6,7 @@ shared_library("LibJS") {
     # FIXME: Why does LibSyntax need to depend on WindowServer headers?
     "//Userland",
   ]
+  cflags_cc = [ "-fno-omit-frame-pointer" ]
   deps = [
     "//AK",
     "//Userland/Libraries/LibCore",