Narrow the scope of writable code to the forwarding phase of become instead of the whole isolate re…

runtime/vm/isolate_reload.cc

Index: runtime/vm/isolate_reload.cc
diff --git a/runtime/vm/isolate_reload.cc b/runtime/vm/isolate_reload.cc
index 8de0e283f0feaaba3299f70889c3ee964d24bbd3..583341182337ad54365cee2f101074df1a4b7c1b 100644
--- a/runtime/vm/isolate_reload.cc
+++ b/runtime/vm/isolate_reload.cc
@@ -463,11 +463,6 @@ void IsolateReloadContext::Reload(bool force_reload) {
   // Disable the background compiler while we are performing the reload.
   BackgroundCompiler::Disable();
 
-  if (FLAG_write_protect_code) {
-    // Disable code page write protection while we are reloading.
-    I->heap()->WriteProtectCode(false);
-  }
-
   // Ensure all functions on the stack have unoptimized code.
   EnsuredUnoptimizedCodeForStack();
   // Deoptimize all code that had optimizing decisions that are dependent on
@@ -541,11 +536,6 @@ void IsolateReloadContext::FinalizeLoading() {
   // information from scratch.
   RebuildDirectSubclasses();
 
-  if (FLAG_write_protect_code) {
-    // Re-enable code page write protection.
-    I->heap()->WriteProtectCode(true);
-  }
-
   BackgroundCompiler::Enable();
 
   reload_aborted_ = HasReasonsForCancelling();