Fix approximation of CanDeoptimize() and other small store elimination fixes.

src/hydrogen-instructions.cc

Index: src/hydrogen-instructions.cc
diff --git a/src/hydrogen-instructions.cc b/src/hydrogen-instructions.cc
index b822d8437f1cdff43039925e711f4e403f549905..7a40dbe6da04ad3301d1c10d651834d08c75f1f4 100644
--- a/src/hydrogen-instructions.cc
+++ b/src/hydrogen-instructions.cc
@@ -863,7 +863,6 @@ bool HInstruction::CanDeoptimize() {
     case HValue::kDateField:
     case HValue::kDebugBreak:
     case HValue::kDeclareGlobals:
-    case HValue::kDiv:
     case HValue::kDummyUse:
     case HValue::kEnterInlined:
     case HValue::kEnvironmentMarker:
@@ -890,7 +889,6 @@ bool HInstruction::CanDeoptimize() {
     case HValue::kMapEnumLength:
     case HValue::kMathFloorOfDiv:
     case HValue::kMathMinMax:
-    case HValue::kMod:
     case HValue::kMul:
     case HValue::kOsrEntry:
     case HValue::kParameter:
@@ -937,6 +935,7 @@ bool HInstruction::CanDeoptimize() {
       }
       return false;
     default:
+      // TODO(titzer): kDiv and kMod can deoptimize under some circumstances.
       return true;
   }
 }