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/style/properties/longhand/box.mako.rs

@@ -162,9 +162,8 @@
     }
 
     #[allow(non_camel_case_types)]
-    #[derive(Clone, Copy, Debug, Eq, Hash, PartialEq, ToComputedValue)]
-    #[cfg_attr(feature = "gecko", derive(MallocSizeOf))]
-    #[cfg_attr(feature = "servo", derive(HeapSizeOf, Deserialize, Serialize))]
+    #[derive(Clone, Copy, Debug, Eq, Hash, MallocSizeOf, PartialEq, ToComputedValue)]
+    #[cfg_attr(feature = "servo", derive(Deserialize, Serialize))]
     pub enum SpecifiedValue {
         % for value in values:
             ${to_rust_ident(value)},
@@ -460,9 +459,7 @@ ${helpers.predefined_type("transition-delay",
         pub use super::SpecifiedValue as T;
     }
 
-    #[derive(Clone, Debug, Eq, Hash, PartialEq, ToComputedValue)]
-    #[cfg_attr(feature = "gecko", derive(MallocSizeOf))]
-    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
+    #[derive(Clone, Debug, Eq, Hash, MallocSizeOf, PartialEq, ToComputedValue)]
     pub struct SpecifiedValue(pub Option<KeyframesName>);
 
     impl SpecifiedValue {
@@ -555,9 +552,7 @@ ${helpers.predefined_type("animation-timing-function",
     }
 
     // https://drafts.csswg.org/css-animations/#animation-iteration-count
-    #[cfg_attr(feature = "gecko", derive(MallocSizeOf))]
-    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
-    #[derive(Clone, Debug, PartialEq, ToCss, ToComputedValue)]
+    #[derive(Clone, Debug, MallocSizeOf, PartialEq, ToCss, ToComputedValue)]
     pub enum SpecifiedValue {
         Number(f32),
         Infinite,
@@ -689,9 +684,7 @@ ${helpers.predefined_type(
         use values::computed;
         use values::computed::{Length, LengthOrPercentage};
 
-        #[derive(Clone, Copy, Debug, PartialEq)]
-        #[cfg_attr(feature = "gecko", derive(MallocSizeOf))]
-        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
+        #[derive(Clone, Copy, Debug, MallocSizeOf, PartialEq)]
         pub struct ComputedMatrix {
             pub m11: CSSFloat, pub m12: CSSFloat, pub m13: CSSFloat, pub m14: CSSFloat,
             pub m21: CSSFloat, pub m22: CSSFloat, pub m23: CSSFloat, pub m24: CSSFloat,
@@ -699,9 +692,7 @@ ${helpers.predefined_type(
             pub m41: CSSFloat, pub m42: CSSFloat, pub m43: CSSFloat, pub m44: CSSFloat,
         }
 
-        #[derive(Clone, Copy, Debug, PartialEq)]
-        #[cfg_attr(feature = "gecko", derive(MallocSizeOf))]
-        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
+        #[derive(Clone, Copy, Debug, MallocSizeOf, PartialEq)]
         pub struct ComputedMatrixWithPercents {
             pub m11: CSSFloat, pub m12: CSSFloat, pub m13: CSSFloat, pub m14: CSSFloat,
             pub m21: CSSFloat, pub m22: CSSFloat, pub m23: CSSFloat, pub m24: CSSFloat,
@@ -733,9 +724,7 @@ ${helpers.predefined_type(
             }
         }
 
-        #[derive(Clone, Debug, PartialEq)]
-        #[cfg_attr(feature = "gecko", derive(MallocSizeOf))]
-        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
+        #[derive(Clone, Debug, MallocSizeOf, PartialEq)]
         pub enum ComputedOperation {
             Matrix(ComputedMatrix),
             // For `-moz-transform` matrix and matrix3d.
@@ -767,9 +756,7 @@ ${helpers.predefined_type(
                                count: computed::Integer },
         }
 
-        #[derive(Clone, Debug, PartialEq)]
-        #[cfg_attr(feature = "gecko", derive(MallocSizeOf))]
-        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
+        #[derive(Clone, Debug, MallocSizeOf, PartialEq)]
         pub struct T(pub Option<Vec<ComputedOperation>>);
     }
 
@@ -779,9 +766,7 @@ ${helpers.predefined_type(
     /// Multiple transform functions compose a transformation.
     ///
     /// Some transformations can be expressed by other more general functions.
-    #[derive(Clone, Debug, PartialEq)]
-    #[cfg_attr(feature = "gecko", derive(MallocSizeOf))]
-    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
+    #[derive(Clone, Debug, MallocSizeOf, PartialEq)]
     pub enum SpecifiedOperation {
         /// Represents a 2D 2x3 matrix.
         Matrix(Matrix<Number>),
@@ -970,9 +955,7 @@ ${helpers.predefined_type(
         }
     }
 
-    #[derive(Clone, Debug, PartialEq)]
-    #[cfg_attr(feature = "gecko", derive(MallocSizeOf))]
-    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
+    #[derive(Clone, Debug, MallocSizeOf, PartialEq)]
     pub struct SpecifiedValue(Vec<SpecifiedOperation>);
 
     impl ToCss for SpecifiedValue {
@@ -1688,9 +1671,7 @@ ${helpers.predefined_type("transform-origin",
     }
 
     bitflags! {
-        #[derive(ToComputedValue)]
-        #[cfg_attr(feature = "gecko", derive(MallocSizeOf))]
-        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
+        #[derive(MallocSizeOf, ToComputedValue)]
         pub flags SpecifiedValue: u8 {
             const LAYOUT = 0x01,
             const STYLE = 0x02,
@@ -1829,9 +1810,7 @@ ${helpers.single_keyword("-moz-orient",
         pub use super::SpecifiedValue as T;
     }
 
-    #[derive(Clone, Debug, PartialEq, ToComputedValue)]
-    #[cfg_attr(feature = "gecko", derive(MallocSizeOf))]
-    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
+    #[derive(Clone, Debug, MallocSizeOf, PartialEq, ToComputedValue)]
     pub enum SpecifiedValue {
         Auto,
         AnimateableFeatures(Vec<CustomIdent>),