Remove support for Javascript warnings in the VM.

runtime/vm/flow_graph_optimizer.cc

Index: runtime/vm/flow_graph_optimizer.cc
diff --git a/runtime/vm/flow_graph_optimizer.cc b/runtime/vm/flow_graph_optimizer.cc
index c93a8d67f908c10309915090730c4c594d37dbb9..36a16907f2a9f3e54181698714e4922faf2dab44 100644
--- a/runtime/vm/flow_graph_optimizer.cc
+++ b/runtime/vm/flow_graph_optimizer.cc
@@ -51,7 +51,6 @@ DECLARE_FLAG(bool, precompilation);
 DECLARE_FLAG(bool, polymorphic_with_deopt);
 DECLARE_FLAG(bool, trace_cha);
 DECLARE_FLAG(bool, trace_field_guards);
-DECLARE_FLAG(bool, warn_on_javascript_compatibility);
 
 // Quick access to the current isolate and zone.
 #define I (isolate())
@@ -170,14 +169,6 @@ bool FlowGraphOptimizer::TryCreateICData(InstanceCallInstr* call) {
     // to megamorphic call.
     return false;
   }
-  if (FLAG_warn_on_javascript_compatibility) {
-    // Do not make the instance call megamorphic if the callee needs to decode
-    // the calling code sequence to lookup the ic data and verify if a warning
-    // has already been issued or not.
-    if (call->ic_data()->MayCheckForJSWarning()) {
-      return false;
-    }
-  }
   GrowableArray<intptr_t> class_ids(call->ic_data()->NumArgsTested());
   ASSERT(call->ic_data()->NumArgsTested() <= call->ArgumentCount());
   for (intptr_t i = 0; i < call->ic_data()->NumArgsTested(); i++) {
@@ -4018,15 +4009,6 @@ void FlowGraphOptimizer::ReplaceWithInstanceOf(InstanceCallInstr* call) {
   }
   const ICData& unary_checks =
       ICData::ZoneHandle(Z, call->ic_data()->AsUnaryClassChecks());
-  if (FLAG_warn_on_javascript_compatibility &&
-      !unary_checks.IssuedJSWarning() &&
-      (type.IsIntType() || type.IsDoubleType() || !type.IsInstantiated())) {
-    // No warning was reported yet for this type check, either because it has
-    // not been executed yet, or because no problematic combinations of instance
-    // type and test type have been encountered so far. A warning may still be
-    // reported, so do not replace the instance call.
-    return;
-  }
   if ((unary_checks.NumberOfChecks() > 0) &&
       (unary_checks.NumberOfChecks() <= FLAG_max_polymorphic_checks)) {
     ZoneGrowableArray<intptr_t>* results =
@@ -4108,15 +4090,6 @@ void FlowGraphOptimizer::ReplaceWithTypeCast(InstanceCallInstr* call) {
   ASSERT(!type.IsMalformedOrMalbounded());
   const ICData& unary_checks =
       ICData::ZoneHandle(Z, call->ic_data()->AsUnaryClassChecks());
-  if (FLAG_warn_on_javascript_compatibility &&
-      !unary_checks.IssuedJSWarning() &&
-      (type.IsIntType() || type.IsDoubleType() || !type.IsInstantiated())) {
-    // No warning was reported yet for this type check, either because it has
-    // not been executed yet, or because no problematic combinations of instance
-    // type and test type have been encountered so far. A warning may still be
-    // reported, so do not replace the instance call.
-    return;
-  }
   if ((unary_checks.NumberOfChecks() > 0) &&
       (unary_checks.NumberOfChecks() <= FLAG_max_polymorphic_checks)) {
     ZoneGrowableArray<intptr_t>* results =