boolean expressions with null are never potentially const

runtime/vm/ast.cc

Index: runtime/vm/ast.cc
===================================================================
--- runtime/vm/ast.cc	(revision 29912)
+++ runtime/vm/ast.cc	(working copy)
@@ -255,6 +255,17 @@
 
 bool BinaryOpNode::IsPotentiallyConst() const {
   switch (kind_) {
+    case Token::kOR:
+    case Token::kAND:
+      if (this->left()->IsLiteralNode() &&
+          this->left()->AsLiteralNode()->literal().IsNull()) {
+        return false;
+      }
+      if (this->right()->IsLiteralNode() &&
+          this->right()->AsLiteralNode()->literal().IsNull()) {
+        return false;
+      }
+      // Fall-through intentional.
     case Token::kADD:
     case Token::kSUB:
     case Token::kMUL:
@@ -266,8 +277,6 @@
     case Token::kBIT_AND:
     case Token::kSHL:
     case Token::kSHR:
-    case Token::kOR:
-    case Token::kAND:
       return this->left()->IsPotentiallyConst() &&
           this->right()->IsPotentiallyConst();
     default:
@@ -355,6 +364,10 @@
 
 
 bool UnaryOpNode::IsPotentiallyConst() const {
+  if (this->operand()->IsLiteralNode() &&
+      this->operand()->AsLiteralNode()->literal().IsNull()) {
+    return false;
+  }
   return this->operand()->IsPotentiallyConst();
 }