[baseline] Fix large code object check when compiling on heap

- Fixes the size check to include Code::kHeaderSize.
- Adds a DCHECK in NewEmptyCode.

Bug: v8:11872
Change-Id: I05156bbe42e7efa8aa0e1982c9e2166d7b09ef5b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3015055
Auto-Submit: Victor Gomes <victorgomes@chromium.org>
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#75643}

src/baseline/baseline-compiler.cc

@@ -257,7 +257,8 @@ std::unique_ptr<AssemblerBuffer> AllocateBuffer(
   // TODO(victorgomes): When compiling on heap, we allocate whatever is left
   // over on the page with a minimum of the estimated_size.
   if (code_location == BaselineCompiler::kOnHeap &&
-      estimated_size < heap->MaxRegularHeapObjectSize(AllocationType::kCode)) {
+      Code::SizeFor(estimated_size) <
+          heap->MaxRegularHeapObjectSize(AllocationType::kCode)) {
     // TODO(victorgomes): We're currently underestimating the size of the
     // buffer, since we don't know how big the reloc info will be. We could
     // use a separate zone vector for the RelocInfo.

src/heap/factory.cc

@@ -344,6 +344,7 @@ MaybeHandle<Code> Factory::NewEmptyCode(CodeKind kind, int buffer_size) {
       !V8_ENABLE_THIRD_PARTY_HEAP_BOOL && !heap->code_region().is_empty(),
       heap->code_region().contains(code->address()));
 
+  DCHECK(heap->code_space()->Contains(raw_code));
   return code;
 }