[heap] Better inlining for incremental marking visitor

Bug: 
Change-Id: If88c6deee07b0188bd6177a4cef6a14dd7610392
Reviewed-on: https://chromium-review.googlesource.com/561397Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46443}

src/heap/incremental-marking.cc

@@ -290,7 +290,7 @@ class IncrementalMarkingMarkingVisitor final
     return Parent::VisitNativeContext(map, context);
   }
 
-  inline void VisitPointer(HeapObject* host, Object** p) final {
+  V8_INLINE void VisitPointer(HeapObject* host, Object** p) final {
     Object* target = *p;
     if (target->IsHeapObject()) {
       collector_->RecordSlot(host, p, target);
@@ -298,7 +298,7 @@ class IncrementalMarkingMarkingVisitor final
     }
   }
 
-  inline void VisitPointers(HeapObject* host, Object** start,
+  V8_INLINE void VisitPointers(HeapObject* host, Object** start,
                                Object** end) final {
     for (Object** p = start; p < end; p++) {
       Object* target = *p;