[turbofan] Equip (Field|Element)Access with constructors.

This prevent forgotten field initializations.

Bug: v8:5267
Change-Id: Iaef5f79af360e2400b29afe878f80870c8a64e71
Reviewed-on: https://chromium-review.googlesource.com/970241
Commit-Queue: Jaroslav Sevcik <jarin@chromium.org>
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52049}

src/compiler/simplified-operator.h

@@ -49,6 +49,24 @@ struct FieldAccess {
   MachineType machine_type;       // machine type of the field.
   WriteBarrierKind write_barrier_kind;  // write barrier hint.
 
+  FieldAccess()
+      : base_is_tagged(kTaggedBase),
+        offset(0),
+        type(Type::None()),
+        machine_type(MachineType::None()),
+        write_barrier_kind(kFullWriteBarrier) {}
+
+  FieldAccess(BaseTaggedness base_is_tagged, int offset, MaybeHandle<Name> name,
+              MaybeHandle<Map> map, Type* type, MachineType machine_type,
+              WriteBarrierKind write_barrier_kind)
+      : base_is_tagged(base_is_tagged),
+        offset(offset),
+        name(name),
+        map(map),
+        type(type),
+        machine_type(machine_type),
+        write_barrier_kind(write_barrier_kind) {}
+
   int tag() const { return base_is_tagged == kTaggedBase ? kHeapObjectTag : 0; }
 };
 
@@ -75,6 +93,21 @@ struct ElementAccess {
   MachineType machine_type;       // machine type of the element.
   WriteBarrierKind write_barrier_kind;  // write barrier hint.
 
+  ElementAccess()
+      : base_is_tagged(kTaggedBase),
+        header_size(0),
+        type(Type::None()),
+        machine_type(MachineType::None()),
+        write_barrier_kind(kFullWriteBarrier) {}
+
+  ElementAccess(BaseTaggedness base_is_tagged, int header_size, Type* type,
+                MachineType machine_type, WriteBarrierKind write_barrier_kind)
+      : base_is_tagged(base_is_tagged),
+        header_size(header_size),
+        type(type),
+        machine_type(machine_type),
+        write_barrier_kind(write_barrier_kind) {}
+
   int tag() const { return base_is_tagged == kTaggedBase ? kHeapObjectTag : 0; }
 };