Avoid "=== true" inside code by calling a function that does this for us.

lib/compiler/implementation/ssa/nodes.dart

Index: lib/compiler/implementation/ssa/nodes.dart
diff --git a/lib/compiler/implementation/ssa/nodes.dart b/lib/compiler/implementation/ssa/nodes.dart
index 19f794894f0250e7588c7940155c9b81fbd85197..b822fb0e276454faf32e05efdd1a067a75c0d0dc 100644
--- a/lib/compiler/implementation/ssa/nodes.dart
+++ b/lib/compiler/implementation/ssa/nodes.dart
@@ -1899,6 +1899,7 @@ class HPhi extends HInstruction {
 }
 
 class HRelational extends HInvokeBinary {
+  bool usesBoolifiedInterceptor = false;
   HRelational(HStatic target, HInstruction left, HInstruction right)
       : super(target, left, right);
 
@@ -1915,7 +1916,7 @@ class HRelational extends HInvokeBinary {
   }
 
   HType computeTypeFromInputTypes() {
-    if (left.isNumber()) return HType.BOOLEAN;
+    if (left.isNumber() || usesBoolifiedInterceptor) return HType.BOOLEAN;
     return HType.UNKNOWN;
   }
 
@@ -1949,7 +1950,7 @@ class HEquals extends HRelational {
   }
 
   HType computeTypeFromInputTypes() {
-    if (builtin) return HType.BOOLEAN;
+    if (builtin || usesBoolifiedInterceptor) return HType.BOOLEAN;
     return HType.UNKNOWN;
   }