Revert of [heap] Unify the immortal immovable root detection mechanism.

src/compiler/code-generator.cc

Index: src/compiler/code-generator.cc
diff --git a/src/compiler/code-generator.cc b/src/compiler/code-generator.cc
index 2e56dd0a484e00cf091f699e8077dcbf2612b06e..6b9a8b86c6560794e57ab33cf8d4032389f69e0c 100644
--- a/src/compiler/code-generator.cc
+++ b/src/compiler/code-generator.cc
@@ -220,12 +220,8 @@
 
 bool CodeGenerator::IsMaterializableFromRoot(
     Handle<HeapObject> object, Heap::RootListIndex* index_return) {
-  Heap::RootListIndex index;
-  if (linkage()->GetIncomingDescriptor()->IsJSFunctionCall() &&
-      isolate()->heap()->GetRootListIndex(*object, &index) &&
-      !Heap::RootCanBeWrittenAfterInitialization(index)) {
-    *index_return = index;
-    return true;
+  if (linkage()->GetIncomingDescriptor()->IsJSFunctionCall()) {
+    return isolate()->heap()->GetRootListIndex(object, index_return);
   }
   return false;
 }