Move ArtField to native

Add linear alloc. Moved ArtField to be native object. Changed image
writer to put ArtFields after the mirror section.

Savings:
2MB on low ram devices
4MB on normal devices

Total PSS measurements before (normal N5, 95s after shell start):
Image size: 7729152 bytes
23112 kB: .NonMoving
23212 kB: .NonMoving
22868 kB: .NonMoving
23072 kB: .NonMoving
22836 kB: .NonMoving
19618 kB: .Zygote
19850 kB: .Zygote
19623 kB: .Zygote
19924 kB: .Zygote
19612 kB: .Zygote
Avg: 42745.4 kB

After:
Image size: 7462912 bytes
17440 kB: .NonMoving
16776 kB: .NonMoving
16804 kB: .NonMoving
17812 kB: .NonMoving
16820 kB: .NonMoving
18788 kB: .Zygote
18856 kB: .Zygote
19064 kB: .Zygote
18841 kB: .Zygote
18629 kB: .Zygote
3499 kB: .LinearAlloc
3408 kB: .LinearAlloc
3424 kB: .LinearAlloc
3600 kB: .LinearAlloc
3436 kB: .LinearAlloc
Avg: 39439.4 kB

No reflection performance changes.

Bug: 19264997
Bug: 17643507

Change-Id: I10c73a37913332080aeb978c7c94713bdfe4fe1c
diff --git a/runtime/mirror/object.h b/runtime/mirror/object.h
index cfc8549..bfd5d4d 100644
--- a/runtime/mirror/object.h
+++ b/runtime/mirror/object.h
@@ -24,6 +24,7 @@
 
 namespace art {
 
+class ArtField;
 class ImageWriter;
 class LockWord;
 class Monitor;
@@ -33,7 +34,6 @@
 
 namespace mirror {
 
-class ArtField;
 class ArtMethod;
 class Array;
 class Class;
@@ -191,12 +191,6 @@
   template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
   ArtMethod* AsArtMethod() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
 
-  template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags,
-           ReadBarrierOption kReadBarrierOption = kWithReadBarrier>
-  bool IsArtField() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
-  template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
-  ArtField* AsArtField() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
-
   template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
   bool IsReferenceInstance() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
   template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>