Eliminate overflow check for non-overflowing smi << operations.

runtime/vm/intermediate_language_arm64.cc

Index: runtime/vm/intermediate_language_arm64.cc
===================================================================
--- runtime/vm/intermediate_language_arm64.cc	(revision 37537)
+++ runtime/vm/intermediate_language_arm64.cc	(working copy)
@@ -2506,7 +2506,7 @@
 
 static void EmitSmiShiftLeft(FlowGraphCompiler* compiler,
                              BinarySmiOpInstr* shift_left) {
-  const bool is_truncating = shift_left->is_truncating();
+  const bool is_truncating = shift_left->IsTruncating();
   const LocationSummary& locs = *shift_left->locs();
   const Register left = locs.in(0).reg();
   const Register result = locs.out(0).reg();
@@ -2630,7 +2630,7 @@
                                                        bool opt) const {
   const intptr_t kNumInputs = 2;
   const intptr_t kNumTemps =
-      (((op_kind() == Token::kSHL) && !is_truncating()) ||
+      (((op_kind() == Token::kSHL) && !IsTruncating()) ||
        (op_kind() == Token::kSHR)) ? 1 : 0;
   LocationSummary* summary = new(isolate) LocationSummary(
       isolate, kNumInputs, kNumTemps, LocationSummary::kNoCall);
@@ -2653,7 +2653,7 @@
   }
   summary->set_in(0, Location::RequiresRegister());
   summary->set_in(1, Location::RegisterOrSmiConstant(right()));
-  if (((op_kind() == Token::kSHL) && !is_truncating()) ||
+  if (((op_kind() == Token::kSHL) && !IsTruncating()) ||
       (op_kind() == Token::kSHR)) {
     summary->set_temp(0, Location::RequiresRegister());
   }
@@ -2670,7 +2670,6 @@
     return;
   }
 
-  ASSERT(!is_truncating());
   const Register left = locs()->in(0).reg();
   const Register result = locs()->out(0).reg();
   Label* deopt = NULL;