Fix windows compilation

Prior to this CL compilation fails with:

- 'error: offset of on non-standard-layout type' due to offsetof()
- 'Assertion failed: vector subscript out of range' due to the OOB vector subscripts

Change-Id: I8751fafd1058ca839de832267811f8f1f47c53fe
Reviewed-on: https://chromium-review.googlesource.com/c/1400404Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58616}

src/heap/heap.cc

@@ -2193,8 +2193,8 @@ void Heap::ExternalStringTable::IterateAll(RootVisitor* v) {
   if (!old_space_strings_.empty()) {
     v->VisitRootPointers(
         Root::kExternalStringsTable, nullptr,
-        FullObjectSlot(&old_space_strings_[0]),
-        FullObjectSlot(&old_space_strings_[old_space_strings_.size()]));
+        FullObjectSlot(old_space_strings_.data()),
+        FullObjectSlot(old_space_strings_.data() + old_space_strings_.size()));
   }
 }
 
@@ -2206,8 +2206,8 @@ void Heap::UpdateNewSpaceReferencesInExternalStringTable(
 void Heap::ExternalStringTable::UpdateReferences(
     Heap::ExternalStringTableUpdaterCallback updater_func) {
   if (old_space_strings_.size() > 0) {
-    FullObjectSlot start(&old_space_strings_[0]);
-    FullObjectSlot end(&old_space_strings_[old_space_strings_.size()]);
+    FullObjectSlot start(old_space_strings_.data());
+    FullObjectSlot end(old_space_strings_.data() + old_space_strings_.size());
     for (FullObjectSlot p = start; p < end; ++p)
       p.store(updater_func(heap_, p));
   }

src/microtask-queue.cc

@@ -18,11 +18,11 @@ namespace v8 {
 namespace internal {
 
 const size_t MicrotaskQueue::kRingBufferOffset =
-    offsetof(MicrotaskQueue, ring_buffer_);
+    OFFSET_OF(MicrotaskQueue, ring_buffer_);
 const size_t MicrotaskQueue::kCapacityOffset =
-    offsetof(MicrotaskQueue, capacity_);
-const size_t MicrotaskQueue::kSizeOffset = offsetof(MicrotaskQueue, size_);
-const size_t MicrotaskQueue::kStartOffset = offsetof(MicrotaskQueue, start_);
+    OFFSET_OF(MicrotaskQueue, capacity_);
+const size_t MicrotaskQueue::kSizeOffset = OFFSET_OF(MicrotaskQueue, size_);
+const size_t MicrotaskQueue::kStartOffset = OFFSET_OF(MicrotaskQueue, start_);
 
 const intptr_t MicrotaskQueue::kMinimumCapacity = 8;