After a dynamic call, refine the receiver type by looking at the potential targets of that call.

sdk/lib/_internal/compiler/implementation/ssa/nodes.dart

Index: sdk/lib/_internal/compiler/implementation/ssa/nodes.dart
===================================================================
--- sdk/lib/_internal/compiler/implementation/ssa/nodes.dart	(revision 22031)
+++ sdk/lib/_internal/compiler/implementation/ssa/nodes.dart	(working copy)
@@ -617,8 +617,8 @@
    */
   void rewriteWithBetterUser(HInstruction from, HInstruction to) {
     Link<HCheck> better = const Link<HCheck>();
-    for (HInstruction user in to.usedBy) {
-      if (user is HCheck && identical((user as HCheck).checkedInput, to)) {
+    for (var user in to.usedBy) {
+      if (user != from && user is HCheck && user.checkedInput == to) {
         better = better.prepend(user);
       }
     }
@@ -930,6 +930,11 @@
     return buffer.toString();
   }
 
+  nonCheck(instruction) {
+    while (instruction is HCheck) instruction = instruction.checkedInput;
+    return instruction;
+  }
+
   bool gvnEquals(HInstruction other) {
     assert(useGvn() && other.useGvn());
     // Check that the type and the flags match.
@@ -942,7 +947,9 @@
     final List<HInstruction> otherInputs = other.inputs;
     if (inputsLength != otherInputs.length) return false;
     for (int i = 0; i < inputsLength; i++) {
-      if (!identical(inputs[i], otherInputs[i])) return false;
+      if (nonCheck(inputs[i]) != nonCheck(otherInputs[i])) {
+        return false;
+      }
     }
     // Check that the data in the instruction matches.
     return dataEquals(other);
@@ -952,7 +959,7 @@
     int result = typeCode();
     int length = inputs.length;
     for (int i = 0; i < length; i++) {
-      result = (result * 19) + (inputs[i].id) + (result >> 7);
+      result = (result * 19) + (nonCheck(inputs[i]).id) + (result >> 7);
     }
     return result;
   }
@@ -1398,6 +1405,14 @@
   }
   toString() => 'invoke dynamic getter: $selector';
   accept(HVisitor visitor) => visitor.visitInvokeDynamicGetter(this);
+
+  int typeCode() => HInstruction.FIELD_GET_TYPECODE;
+  bool typeEquals(other) => other is HFieldGet || other is HInvokeDynamicGetter;
+  bool dataEquals(other) {
+    return other is HFieldGet
+        ? other.element.name == selector.name
+        : super.dataEquals(other);
+  }
 }
 
 class HInvokeDynamicSetter extends HInvokeDynamicField {
@@ -1485,8 +1500,12 @@
   accept(HVisitor visitor) => visitor.visitFieldGet(this);
 
   int typeCode() => HInstruction.FIELD_GET_TYPECODE;
-  bool typeEquals(other) => other is HFieldGet;
-  bool dataEquals(HFieldGet other) => element == other.element;
+  bool typeEquals(other) => other is HFieldGet || other is HInvokeDynamicGetter;
+  bool dataEquals(other) {
+    return other is HInvokeDynamicGetter
+        ? element.name == other.selector.name
+        : element == other.element;
+  }
   String toString() => "FieldGet $element";
 }