Revert to per-process shared lock for author-origin stylesheets

Fixes https://github.com/servo/servo/issues/16097
Reopens https://github.com/servo/servo/issues/16027

Cargo.lock

@@ -2249,6 +2249,7 @@ dependencies = [
  "ipc-channel 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "js 0.1.4 (git+https://github.com/servo/rust-mozjs)",
  "jstraceable_derive 0.0.1",
+ "lazy_static 0.2.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "libc 0.2.21 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
  "mime 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",

components/script/Cargo.toml

@@ -54,6 +54,7 @@ image = "0.12"
 ipc-channel = "0.7"
 js = {git = "https://github.com/servo/rust-mozjs", features = ["promises"]}
 jstraceable_derive = {path = "../jstraceable_derive"}
+lazy_static = "0.2"
 libc = "0.2"
 log = "0.3.5"
 mime = "0.2.1"

components/script/dom/document.rs

@@ -2132,7 +2132,21 @@ impl Document {
             scripts: Default::default(),
             anchors: Default::default(),
             applets: Default::default(),
-            style_shared_lock: StyleSharedRwLock::new(),
+            style_shared_lock: {
+                lazy_static! {
+                    /// Per-process shared lock for author-origin stylesheets
+                    ///
+                    /// FIXME: make it per-document or per-pipeline instead:
+                    /// https://github.com/servo/servo/issues/16027
+                    /// (Need to figure out what to do with the style attribute
+                    /// of elements adopted into another document.)
+                    static ref PER_PROCESS_AUTHOR_SHARED_LOCK: StyleSharedRwLock = {
+                        StyleSharedRwLock::new()
+                    };
+                }
+                PER_PROCESS_AUTHOR_SHARED_LOCK.clone()
+                //StyleSharedRwLock::new()
+            },
             stylesheets: DOMRefCell::new(None),
             stylesheets_changed_since_reflow: Cell::new(false),
             stylesheet_list: MutNullableJS::new(None),

components/script/lib.rs

@@ -60,6 +60,8 @@ extern crate ipc_channel;
 extern crate js;
 #[macro_use]
 extern crate jstraceable_derive;
+#[macro_use]
+extern crate lazy_static;
 extern crate libc;
 #[macro_use]
 extern crate log;