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/root.rs

@@ -30,9 +30,9 @@ use dom::bindings::reflector::{DomObject, Reflector};
 use dom::bindings::trace::JSTraceable;
 use dom::bindings::trace::trace_reflector;
 use dom::node::Node;
-use heapsize::HeapSizeOf;
 use js::jsapi::{JSObject, JSTracer, Heap};
 use js::rust::GCMethods;
+use malloc_size_of::{MallocSizeOf, MallocSizeOfOps};
 use mitochondria::OnceCell;
 use nonzero::NonZero;
 use script_layout_interface::TrustedNodeAddress;
@@ -157,12 +157,12 @@ impl<T: DomObject> DomRoot<T> {
     }
 }
 
-impl<T> HeapSizeOf for DomRoot<T>
+impl<T> MallocSizeOf for DomRoot<T>
 where
-    T: DomObject + HeapSizeOf,
+    T: DomObject + MallocSizeOf,
 {
-    fn heap_size_of_children(&self) -> usize {
-        (**self).heap_size_of_children()
+    fn size_of(&self, ops: &mut MallocSizeOfOps) -> usize {
+        (**self).size_of(ops)
     }
 }
 
@@ -317,8 +317,8 @@ pub struct Dom<T> {
 
 // Dom<T> is similar to Rc<T>, in that it's not always clear how to avoid double-counting.
 // For now, we choose not to follow any such pointers.
-impl<T> HeapSizeOf for Dom<T> {
-    fn heap_size_of_children(&self) -> usize {
+impl<T> MallocSizeOf for Dom<T> {
+    fn size_of(&self, _ops: &mut MallocSizeOfOps) -> usize {
         0
     }
 }
@@ -516,9 +516,9 @@ impl<T: DomObject> MutDom<T> {
     }
 }
 
-impl<T: DomObject> HeapSizeOf for MutDom<T> {
-    fn heap_size_of_children(&self) -> usize {
-        // See comment on HeapSizeOf for Dom<T>.
+impl<T: DomObject> MallocSizeOf for MutDom<T> {
+    fn size_of(&self, _ops: &mut MallocSizeOfOps) -> usize {
+        // See comment on MallocSizeOf for Dom<T>.
         0
     }
 }
@@ -635,9 +635,9 @@ impl<T: DomObject> Default for MutNullableDom<T> {
     }
 }
 
-impl<T: DomObject> HeapSizeOf for MutNullableDom<T> {
-    fn heap_size_of_children(&self) -> usize {
-        // See comment on HeapSizeOf for Dom<T>.
+impl<T: DomObject> MallocSizeOf for MutNullableDom<T> {
+    fn size_of(&self, _ops: &mut MallocSizeOfOps) -> usize {
+        // See comment on MallocSizeOf for Dom<T>.
         0
     }
 }
@@ -678,9 +678,9 @@ impl<T: DomObject> Default for DomOnceCell<T> {
     }
 }
 
-impl<T: DomObject> HeapSizeOf for DomOnceCell<T> {
-    fn heap_size_of_children(&self) -> usize {
-        // See comment on HeapSizeOf for Dom<T>.
+impl<T: DomObject> MallocSizeOf for DomOnceCell<T> {
+    fn size_of(&self, _ops: &mut MallocSizeOfOps) -> usize {
+        // See comment on MallocSizeOf for Dom<T>.
         0
     }
 }