Revert "Protect types_propagation receiver type strengthening against many users."

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 235b0555b06fe71c678b1de2b20bdb07288dbce8..756417621fe38ddd4cb6ae024aacc2d4ad1f5ee2 100644
--- a/pkg/compiler/lib/src/ssa/types_propagation.dart
+++ b/pkg/compiler/lib/src/ssa/types_propagation.dart
@@ -361,48 +361,31 @@ class SsaTypePropagator extends HBaseVisitor implements OptimizationPhase {
     TypeMask receiverType = receiver.instructionType;
     instruction.mask = receiverType;
 
-    // Try to specialize the receiver after this call. There are two potentially
-    // expensive tests - are there any uses of the receiver dominated by and
-    // following this call?, and what is the refined type? The first is
-    // expensive if the receiver has many uses, the second is expensive if many
-    // classes implement the selector. So we try to do the least expensive test
-    // first.
-    const int _MAX_QUICK_USERS = 50;
-    if (!instruction.selector.isClosureCall) {
-      TypeMask newType;
-      bool newTypeChanged() {
-        newType = compiler.world.allFunctions
-            .receiverType(instruction.selector, instruction.mask);
-        newType = newType.intersection(receiverType, classWorld);
-        return newType != receiverType;
-      }
-
-      bool hasCandidates() => receiver.dominatedUsers(instruction).length > 1;
-
-      if ((receiver.usedBy.length <= _MAX_QUICK_USERS)
-          ? (hasCandidates() && newTypeChanged())
-          : (newTypeChanged() && hasCandidates())) {
-        var next = instruction.next;
-        if (next is HTypeKnown && next.checkedInput == receiver) {
-          // We already have refined [receiver]. We still update the
-          // type of the [HTypeKnown] instruction because it may have
-          // been refined with a correct type at the time, but
-          // incorrect now.
-          if (next.instructionType != newType) {
-            next.knownType = next.instructionType = newType;
-            addDependentInstructionsToWorkList(next);
-          }
-        } else {
-          assert(newType != receiverType);
-          // Insert a refinement node after the call and update all
-          // users dominated by the call to use that node instead of
-          // [receiver].
-          HTypeKnown converted =
-              new HTypeKnown.witnessed(newType, receiver, instruction);
-          instruction.block.addBefore(instruction.next, converted);
-          receiver.replaceAllUsersDominatedBy(converted.next, converted);
-          addDependentInstructionsToWorkList(converted);
+    // Try to specialize the receiver after this call.
+    if (receiver.dominatedUsers(instruction).length != 1 &&
+        !instruction.selector.isClosureCall) {
+      TypeMask newType = compiler.world.allFunctions
+          .receiverType(instruction.selector, instruction.mask);
+      newType = newType.intersection(receiverType, classWorld);
+      var next = instruction.next;
+      if (next is HTypeKnown && next.checkedInput == receiver) {
+        // We already have refined [receiver]. We still update the
+        // type of the [HTypeKnown] instruction because it may have
+        // been refined with a correct type at the time, but
+        // incorrect now.
+        if (next.instructionType != newType) {
+          next.knownType = next.instructionType = newType;
+          addDependentInstructionsToWorkList(next);
         }
+      } else if (newType != receiverType) {
+        // Insert a refinement node after the call and update all
+        // users dominated by the call to use that node instead of
+        // [receiver].
+        HTypeKnown converted =
+            new HTypeKnown.witnessed(newType, receiver, instruction);
+        instruction.block.addBefore(instruction.next, converted);
+        receiver.replaceAllUsersDominatedBy(converted.next, converted);
+        addDependentInstructionsToWorkList(converted);
       }
     }