[heap] CodeSpaceMemoryModificationScope also handles large pages.

Bug: chromium:774108,v8:6792
Change-Id: I09ec58f7fdc17f1cc50d9445f8b473e17a584dc1
Reviewed-on: https://chromium-review.googlesource.com/756843Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Commit-Queue: Hannes Payer <hpayer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49185}

src/heap/heap-inl.h

@@ -601,12 +601,26 @@ CodeSpaceMemoryModificationScope::CodeSpaceMemoryModificationScope(Heap* heap)
     : heap_(heap) {
   if (FLAG_write_protect_code_memory) {
     heap_->code_space()->SetReadAndWritable();
+    LargePage* page = heap_->lo_space()->first_page();
+    while (page != nullptr) {
+      if (page->IsFlagSet(MemoryChunk::IS_EXECUTABLE)) {
+        page->SetReadAndWritable();
+      }
+      page = page->next_page();
+    }
   }
 }
 
 CodeSpaceMemoryModificationScope::~CodeSpaceMemoryModificationScope() {
   if (FLAG_write_protect_code_memory) {
     heap_->code_space()->SetReadAndExecutable();
+    LargePage* page = heap_->lo_space()->first_page();
+    while (page != nullptr) {
+      if (page->IsFlagSet(MemoryChunk::IS_EXECUTABLE)) {
+        page->SetReadAndExecutable();
+      }
+      page = page->next_page();
+    }
   }
 }