Port SIMD types from dart:scalarlist to dart:typeddata.

runtime/vm/object.h

Index: runtime/vm/object.h
diff --git a/runtime/vm/object.h b/runtime/vm/object.h
index 6e464d727bfec5fae76428d51c0ce9b313837876..535e7562f6ad219ca900b05af5881216eed6f874 100644
--- a/runtime/vm/object.h
+++ b/runtime/vm/object.h
@@ -4952,6 +4952,12 @@ class TypedData : public Instance {
   TYPED_GETTER_SETTER(Uint64, uint64_t)
   TYPED_GETTER_SETTER(Float32, float)
   TYPED_GETTER_SETTER(Float64, double)
+  simd_value_t GetFloat32x4(intptr_t byte_offset) const {
+    return simd_value_safe_load(DataAddr(byte_offset));
+  }
+  void SetFloat32x4(intptr_t byte_offset, simd_value_t value) const {
+    simd_value_safe_store(DataAddr(byte_offset), value);
+  }
 
   static intptr_t length_offset() {
     return OFFSET_OF(RawTypedData, length_);
@@ -5029,6 +5035,12 @@ class ExternalTypedData : public Instance {
   TYPED_GETTER_SETTER(Uint64, uint64_t)
   TYPED_GETTER_SETTER(Float32, float)
   TYPED_GETTER_SETTER(Float64, double)
+  simd_value_t GetFloat32x4(intptr_t byte_offset) const {
+    return simd_value_safe_load(DataAddr(byte_offset));
+  }
+  void SetFloat32x4(intptr_t byte_offset, simd_value_t value) const {
+    simd_value_safe_store(DataAddr(byte_offset), value);
+  }
 
   FinalizablePersistentHandle* AddFinalizer(
       void* peer, Dart_WeakPersistentHandleFinalizer callback) const;