Replace all uses of the heapsize crate with malloc_size_of.

Servo currently uses `heapsize`, but Stylo/Gecko use `malloc_size_of`.
`malloc_size_of` is better -- it handles various cases that `heapsize` does not
-- so this patch changes Servo to use `malloc_size_of`.

This patch makes the following changes to the `malloc_size_of` crate.

- Adds `MallocSizeOf` trait implementations for numerous types, some built-in
  (e.g. `VecDeque`), some external and Servo-only (e.g. `string_cache`).

- Makes `enclosing_size_of_op` optional, because vanilla jemalloc doesn't
  support that operation.

- For `HashSet`/`HashMap`, falls back to a computed estimate when
  `enclosing_size_of_op` isn't available.

- Adds an extern "C" `malloc_size_of` function that does the actual heap
  measurement; this is based on the same functions from the `heapsize` crate.

This patch makes the following changes elsewhere.

- Converts all the uses of `heapsize` to instead use `malloc_size_of`.

- Disables the "heapsize"/"heap_size" feature for the external crates that
  provide it.

- Removes the `HeapSizeOf` implementation from `hashglobe`.

- Adds `ignore` annotations to a few `Rc`/`Arc`, because `malloc_size_of`
  doesn't derive those types, unlike `heapsize`.

components/script/dom/bindings/utils.rs

@@ -13,7 +13,6 @@ use dom::bindings::inheritance::TopTypeId;
 use dom::bindings::str::DOMString;
 use dom::bindings::trace::trace_object;
 use dom::windowproxy;
-use heapsize::HeapSizeOf;
 use js;
 use js::JS_CALLEE;
 use js::glue::{CallJitGetterOp, CallJitMethodOp, CallJitSetterOp, IsWrapper};
@@ -32,6 +31,7 @@ use js::jsapi::{JS_StringHasLatin1Chars, MutableHandleValue, ObjectOpResult};
 use js::jsval::{JSVal, UndefinedValue};
 use js::rust::{GCMethods, ToString, get_object_class, is_dom_class};
 use libc;
+use malloc_size_of::{MallocSizeOf, MallocSizeOfOps};
 use std::ffi::CString;
 use std::os::raw::{c_char, c_void};
 use std::ptr;
@@ -40,14 +40,14 @@ use std::slice;
 /// Proxy handler for a WindowProxy.
 pub struct WindowProxyHandler(pub *const libc::c_void);
 
-impl HeapSizeOf for WindowProxyHandler {
-    fn heap_size_of_children(&self) -> usize {
+impl MallocSizeOf for WindowProxyHandler {
+    fn size_of(&self, _ops: &mut MallocSizeOfOps) -> usize {
         // FIXME(#6907) this is a pointer to memory allocated by `new` in NewProxyHandler in rust-mozjs.
         0
     }
 }
 
-#[derive(HeapSizeOf, JSTraceable)]
+#[derive(JSTraceable, MallocSizeOf)]
 /// Static data associated with a global object.
 pub struct GlobalStaticData {
     /// The WindowProxy proxy handler for this global.
@@ -88,8 +88,8 @@ pub struct DOMClass {
     /// The type ID of that interface.
     pub type_id: TopTypeId,
 
-    /// The HeapSizeOf function wrapper for that interface.
-    pub heap_size_of: unsafe fn(*const c_void) -> usize,
+    /// The MallocSizeOf function wrapper for that interface.
+    pub malloc_size_of: unsafe fn(ops: &mut MallocSizeOfOps, *const c_void) -> usize,
 
     /// The `Globals` flag for this global interface, if any.
     pub global: InterfaceObjectMap::Globals,