Fix some warnings.

lib/compiler/implementation/ssa/value_range_analyzer.dart

Index: lib/compiler/implementation/ssa/value_range_analyzer.dart
diff --git a/lib/compiler/implementation/ssa/value_range_analyzer.dart b/lib/compiler/implementation/ssa/value_range_analyzer.dart
index b715b278219bd0bc68c37979da5da13a3104320c..b868939647be787d1f20ed2d9d4431526d385291 100644
--- a/lib/compiler/implementation/ssa/value_range_analyzer.dart
+++ b/lib/compiler/implementation/ssa/value_range_analyzer.dart
@@ -189,7 +189,7 @@ class LengthValue extends InstructionValue {
 class OperationValue extends Value {
   final Value left;
   final Value right;
-  final Operation operation;
+  final BinaryOperation operation;
   OperationValue(this.left, this.right, this.operation);
 
   bool operator ==(other) {
@@ -398,7 +398,8 @@ class SsaValueRangeAnalyzer extends HBaseVisitor implements OptimizationPhase {
 
   Range visitConstant(HConstant constant) {
     if (!constant.isInteger(types)) return const Range.unbound();
-    Value value = new IntValue(constant.constant.value);
+    IntConstant constantInt = constant.constant;
+    Value value = new IntValue(constantInt.value);
     return new Range(value, value);
   }