Remove --stop-at flag from several backends.

src/mips/builtins-mips.cc

Index: src/mips/builtins-mips.cc
diff --git a/src/mips/builtins-mips.cc b/src/mips/builtins-mips.cc
index edb680dbba20978fc1c1440e69f4dbb3cce94d94..608f9477d9ae3dc37d638e4d479dfa5e329311e7 100644
--- a/src/mips/builtins-mips.cc
+++ b/src/mips/builtins-mips.cc
@@ -1028,7 +1028,6 @@ void Builtins::Generate_InterpreterEntryTrampoline(MacroAssembler* masm) {
   // fullcodegen's prologue:
   //  - Support profiler (specifically profiling_counter).
   //  - Call ProfileEntryHookStub when isolate has a function_entry_hook.
-  //  - Allow simulator stop operations if FLAG_stop_at is set.
   //  - Code aging of the BytecodeArray object.
 
   // Load bytecode offset and dispatch table into registers.