Auto merge of #15406 - saneyuki:rm-unused-alloc-gfx, r=jdm

Use 'alloc' gate only for platforms which use freetype in gfx

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- [ ] These changes fix #__ (github issue number if applicable).

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components/gfx/lib.rs

@@ -6,7 +6,7 @@
 #![feature(cfg_target_feature)]
 #![cfg_attr(any(target_os = "linux", target_os = "android"), feature(heap_api))]
 
-#![feature(alloc)]
+#![cfg_attr(any(target_os = "linux", target_os = "android"), feature(alloc))]
 #![feature(box_syntax)]
 #![feature(plugin)]
 #![feature(range_contains)]
@@ -16,6 +16,9 @@
 
 #![deny(unsafe_code)]
 
+#[cfg(any(target_os = "linux", target_os = "android"))]
+extern crate alloc;
+
 extern crate app_units;
 #[macro_use]
 extern crate bitflags;

components/gfx/platform/freetype/font_context.rs

@@ -2,8 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-extern crate alloc;
-
+use alloc::heap;
 use freetype::freetype::FT_Add_Default_Modules;
 use freetype::freetype::FT_Done_Library;
 use freetype::freetype::FT_Library;
@@ -11,7 +10,6 @@ use freetype::freetype::FT_Memory;
 use freetype::freetype::FT_MemoryRec_;
 use freetype::freetype::FT_New_Library;
 use heapsize::{HeapSizeOf, heap_size_of};
-use self::alloc::heap;
 use std::os::raw::{c_long, c_void};
 use std::ptr;
 use std::rc::Rc;