auto merge of #8475 : kmcallister/rust/stack_segment, r=brson,brson

Servo needs to tell SpiderMonkey about the stack bounds.

r? @brson

src/libstd/rt/mod.rs

@@ -112,7 +112,7 @@ mod message_queue;
 mod sleeper_list;
 
 /// Stack segments and caching.
-mod stack;
+pub mod stack;
 
 /// CPU context swapping.
 mod context;

src/libstd/rt/task.rs

@@ -64,7 +64,7 @@ pub struct Coroutine {
     /// The segment of stack on which the task is currently running or
     /// if the task is blocked, on which the task will resume
     /// execution.
-    priv current_stack_segment: StackSegment,
+    current_stack_segment: StackSegment,
     /// Always valid if the task is alive and not running.
     saved_context: Context
 }