Use better JS engine defaults

This adds in preferences for all the SM 39 available options (as
retrieved from Gecko), and uses the same defaults as Gecko. A few
properties are not supported yet, and incremental GC is still always
disabled regardless of the preference setting.

This also adds back in the options that were accidentally deleted when
\#10342 was rebased, which moved things from script_thread.rs to
script_runtime.rs.

1 files changed, 2 insertions, 1 deletions

diff --git a/components/script/script_thread.rs b/components/script/script_thread.rs
index b9027c96390..7cb24e110bc 100644
--- a/components/script/script_thread.rs
+++ b/components/script/script_thread.rs
@@ -52,7 +52,8 @@ use hyper::mime::{Mime, SubLevel, TopLevel};
 use ipc_channel::ipc::{self, IpcSender};
 use ipc_channel::router::ROUTER;
 use js::jsapi::{DOMProxyShadowsResult, HandleId, HandleObject, RootedValue};
-use js::jsapi::{JSAutoRequest, JSContext, JS_SetWrapObjectCallbacks, JSTracer};
+use js::jsapi::{JSAutoRequest, JS_SetWrapObjectCallbacks};
+use js::jsapi::{JSContext, JSTracer};
 use js::jsval::UndefinedValue;
 use js::rust::Runtime;
 use layout_interface::{ReflowQueryType};