VM: Cache instructions entry point in RawFunction/RawCode.

runtime/vm/gc_marker.cc

Index: runtime/vm/gc_marker.cc
diff --git a/runtime/vm/gc_marker.cc b/runtime/vm/gc_marker.cc
index 79b5a86ea8dbe689eb45201238debedd458797fa..b8da4fe42382385090068c855475b65a9e2ddba2 100644
--- a/runtime/vm/gc_marker.cc
+++ b/runtime/vm/gc_marker.cc
@@ -296,6 +296,9 @@ class MarkingVisitor : public ObjectPointerVisitor {
         func->StorePointer(
             &(func->ptr()->instructions_),
             StubCode::LazyCompile_entry()->code()->ptr()->instructions_);
+        uword entry_point = StubCode::LazyCompile_entry()->EntryPoint();
+        func->ptr()->entry_point_ = entry_point;
+
         if (FLAG_log_code_drop) {
           // NOTE: This code runs while GC is in progress and runs within
           // a NoHandleScope block. Hence it is not okay to use a regular Zone