[modules] Make ModuleInfoEntry a Struct rather than FixedArray.

src/objects-debug.cc

Index: src/objects-debug.cc
diff --git a/src/objects-debug.cc b/src/objects-debug.cc
index 362fa4074c199f55a3fbac6b414802a0289327dd..1fde5b8789b2619eb35d3309d1ced3e818ec9d64 100644
--- a/src/objects-debug.cc
+++ b/src/objects-debug.cc
@@ -1000,6 +1000,24 @@ void JSFixedArrayIterator::JSFixedArrayIteratorVerify() {
   CHECK_LE(index(), array()->length());
 }
 
+void ModuleInfoEntry::ModuleInfoEntryVerify() {
+  Isolate* isolate = GetIsolate();
+  CHECK(IsModuleInfoEntry());
+
+  CHECK(export_name()->IsUndefined(isolate) || export_name()->IsString());
+  CHECK(local_name()->IsUndefined(isolate) || local_name()->IsString());
+  CHECK(import_name()->IsUndefined(isolate) || import_name()->IsString());
+
+  VerifySmiField(kModuleRequestOffset);
+  VerifySmiField(kCellIndexOffset);
+  VerifySmiField(kBegPosOffset);
+  VerifySmiField(kEndPosOffset);
+
+  CHECK_IMPLIES(import_name()->IsString(), module_request() >= 0);
+  CHECK_IMPLIES(export_name()->IsString() && import_name()->IsString(),
+                local_name()->IsUndefined(isolate));
+}
+
 void Module::ModuleVerify() {
   CHECK(IsModule());