Remove the show-compositor-borders debug option

This was used by the old compositor of which only the ghostly echoes of
old commits remain. Since it's been unused for quite some time, it is
probably safe to remove it.

components/config/opts.rs

@@ -86,10 +86,6 @@ pub struct Opts {
     /// browser engines.
     pub bubble_inline_sizes_separately: bool,
 
-    /// True if we should show borders on all layers and tiles for
-    /// debugging purposes (`--show-debug-borders`).
-    pub show_debug_borders: bool,
-
     /// True if we should show borders on all fragments for debugging purposes
     /// (`--show-debug-fragment-borders`).
     pub show_debug_fragment_borders: bool,
@@ -285,9 +281,6 @@ pub struct DebugOptions {
     /// Enable all heartbeats for profiling.
     pub profile_heartbeats: bool,
 
-    /// Paint borders along layer and tile boundaries.
-    pub show_compositor_borders: bool,
-
     /// Paint borders along fragment boundaries.
     pub show_fragment_borders: bool,
 
@@ -369,7 +362,6 @@ impl DebugOptions {
                 "relayout-event" => self.relayout_event = true,
                 "profile-script-events" => self.profile_script_events = true,
                 "profile-heartbeats" => self.profile_heartbeats = true,
-                "show-compositor-borders" => self.show_compositor_borders = true,
                 "show-fragment-borders" => self.show_fragment_borders = true,
                 "show-parallel-paint" => self.show_parallel_paint = true,
                 "show-parallel-layout" => self.show_parallel_layout = true,
@@ -525,7 +517,6 @@ pub fn default_opts() -> Opts {
         headless: true,
         hard_fail: true,
         bubble_inline_sizes_separately: false,
-        show_debug_borders: false,
         show_debug_fragment_borders: false,
         show_debug_parallel_paint: false,
         show_debug_parallel_layout: false,
@@ -841,7 +832,6 @@ pub fn from_cmdline_args(args: &[String]) -> ArgumentParsingResult {
         sandbox: opt_match.opt_present("S"),
         random_pipeline_closure_probability: random_pipeline_closure_probability,
         random_pipeline_closure_seed: random_pipeline_closure_seed,
-        show_debug_borders: debug_options.show_compositor_borders,
         show_debug_fragment_borders: debug_options.show_fragment_borders,
         show_debug_parallel_paint: debug_options.show_parallel_paint,
         show_debug_parallel_layout: debug_options.show_parallel_layout,