Remove special casing of == null

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

Index: pkg/compiler/lib/src/ssa/builder_kernel.dart
diff --git a/pkg/compiler/lib/src/ssa/builder_kernel.dart b/pkg/compiler/lib/src/ssa/builder_kernel.dart
index 9fc1be611ce7de8a39ace6520164826ccf51a7f0..a924a681ca2111a170502ec701844acf55468748 100644
--- a/pkg/compiler/lib/src/ssa/builder_kernel.dart
+++ b/pkg/compiler/lib/src/ssa/builder_kernel.dart
@@ -719,12 +719,6 @@ class KernelSsaGraphBuilder extends ir.Visitor
     graph.finalize();
   }
 
-  /// Pushes a boolean checking [expression] against null.
-  pushCheckNull(HInstruction expression) {
-    push(new HIdentity(expression, graph.addConstantNull(closedWorld), null,
-        commonMasks.boolType));
-  }
-
   @override
   void defaultExpression(ir.Expression expression) {
     // TODO(het): This is only to get tests working.
@@ -2888,9 +2882,6 @@ class KernelSsaGraphBuilder extends ir.Visitor
   // TODO(het): Decide when to inline
   @override
   void visitMethodInvocation(ir.MethodInvocation invocation) {
-    // Handle `x == null` specially. When these come from null-aware operators,
-    // there is no mapping in the astAdapter.
-    if (_handleEqualsNull(invocation)) return;
     invocation.receiver.accept(this);
     HInstruction receiver = pop();
     Selector selector = _elementMap.getSelector(invocation);
@@ -2901,27 +2892,6 @@ class KernelSsaGraphBuilder extends ir.Visitor
             _visitArgumentsForDynamicTarget(selector, invocation.arguments)));
   }
 
-  bool _handleEqualsNull(ir.MethodInvocation invocation) {
-    if (invocation.name.name == '==') {
-      ir.Arguments arguments = invocation.arguments;
-      if (arguments.types.isEmpty &&
-          arguments.positional.length == 1 &&
-          arguments.named.isEmpty) {
-        bool finish(ir.Expression comparand) {
-          comparand.accept(this);
-          pushCheckNull(pop());
-          return true;
-        }
-
-        ir.Expression receiver = invocation.receiver;
-        ir.Expression argument = arguments.positional.first;
-        if (argument is ir.NullLiteral) return finish(receiver);
-        if (receiver is ir.NullLiteral) return finish(argument);
-      }
-    }
-    return false;
-  }
-
   HInterceptor _interceptorFor(HInstruction intercepted) {
     HInterceptor interceptor =
         new HInterceptor(intercepted, commonMasks.nonNullType);