Optimize DateTime properties

pkg/compiler/lib/src/ssa/types_propagation.dart

Index: pkg/compiler/lib/src/ssa/types_propagation.dart
diff --git a/pkg/compiler/lib/src/ssa/types_propagation.dart b/pkg/compiler/lib/src/ssa/types_propagation.dart
index e16641c2ca50137914c59d0b625d9b5a83800ad7..71abe6c3ed5bfa4df8dbb65ad9df38538f69b6fe 100644
--- a/pkg/compiler/lib/src/ssa/types_propagation.dart
+++ b/pkg/compiler/lib/src/ssa/types_propagation.dart
@@ -132,6 +132,11 @@ class SsaTypePropagator extends HBaseVisitor implements OptimizationPhase {
     return instruction.instructionType;
   }
 
+  TypeMask visitTruncatingDivide(HTruncatingDivide instruction) {
+    // Always as initialized.
+    return instruction.instructionType;
+  }
+
   TypeMask visitNegate(HNegate instruction) {
     HInstruction operand = instruction.operand;
     // We have integer subclasses that represent ranges, so widen any int