Make sure we throw the right NSM error when indexing out of range of a variable that can be null.

sdk/lib/_internal/compiler/implementation/ssa/nodes.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of ssa;
 
 abstract class HVisitor<R> {
   R visitAdd(HAdd node);
   R visitBailoutTarget(HBailoutTarget node);
   R visitBitAnd(HBitAnd node);
@@ skipping 1226 matching lines @@
   static const int FULL_CHECK = 1;
   static const int ALWAYS_ABOVE_ZERO = 2;
   static const int ALWAYS_BELOW_LENGTH = 3;
   static const int ALWAYS_TRUE = 4;
   /**
    * Details which tests have been done statically during compilation.
    * Default is that all checks must be performed dynamically.
    */
   int staticChecks = FULL_CHECK;
 
-  HBoundsCheck(length, index) : super(<HInstruction>[length, index]) {
+  HBoundsCheck(length, index, array)
+      : super(<HInstruction>[length, index, array]) {
     instructionType = HType.INTEGER;
   }
 
   HInstruction get length => inputs[1];
   HInstruction get index => inputs[0];
+  HInstruction get array => inputs[2];
   bool isControlFlow() => true;
 
   accept(HVisitor visitor) => visitor.visitBoundsCheck(this);
   int typeCode() => HInstruction.BOUNDS_CHECK_TYPECODE;
   bool typeEquals(other) => other is HBoundsCheck;
   bool dataEquals(HInstruction other) => true;
 }
 
 abstract class HConditionalBranch extends HControlFlow {
   HConditionalBranch(inputs) : super(inputs);
@@ skipping 1465 matching lines @@
   HBasicBlock get start => expression.start;
   HBasicBlock get end {
     // We don't create a switch block if there are no cases.
     assert(!statements.isEmpty);
     return statements.last.end;
   }
 
   bool accept(HStatementInformationVisitor visitor) =>
       visitor.visitSwitchInfo(this);
 }