dart2js cps_ir: Use interceptors for is-checks.

pkg/compiler/lib/src/cps_ir/builtin_operator.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 library builtin_operator;
 // This is shared by the CPS and Tree IRs.
 // Both cps_ir_nodes and tree_ir_nodes import and re-export this file.
 
 /// An operator supported natively in the CPS and Tree IRs using the
 /// `ApplyBuiltinOperator` instructions.
 ///
@@ skipping 85 matching lines @@
   ///
   /// Compiles to `Math.floor(x) === x`
   IsFloor,
 
   /// Returns true if the argument is an integer.
   ///
   /// The argument must be repeated 3 times.
   ///
   /// Compiles to `typeof x === 'number' && Math.floor(x) === x`
   IsNumberAndFloor,
+
+  /// Returns true if the argument is a fixed length Array.
+  ///
+  /// Uses one argument.
+  ///
+  /// Precondition: Argument is a JavaScript Array.

[sra1, 2015/10/06 06:47:58]

I'm pretty sure there are some places where this is not true.
However, this is no worse than what it is replacing.

+  IsFixedLengthJSArray,
+
+  // TODO(sra): Remove this and replace with IsFalsy(IsFixedLengthJSArray(x)).
+  IsExtendableJSArray,
+
+  /// Returns true if the argument is an unmodifiable Array.
+  ///
+  /// Uses one argument.
+  ///
+  /// Precondition: Argument is a JavaScript Array.
+  IsUnmodifiableJSArray,
+
+  // TODO(sra): Remove this and replace with IsFalsy(IsUnmodifiableArray(x)).
+  IsModifiableJSArray,
+
+
+  /// Compiles to
+  ///
+  ///     typeof x === 'object' && x !== null && x.constructor === Array
+  ///
+  /// TODO(sra): Break into individual tests.
+  IsJSArray,
+  ISJSArrayNotNull,
+  IsJSArrayObject,
+  IsJSArrayConstructor,
 }
 
 /// A method supported natively in the CPS and Tree IRs using the
 /// `ApplyBuiltinMethod` instructions.
 /// 
 /// These methods all operate on a distinguished 'object' argument, and
 /// take zero or more additional arguments.
 /// 
 /// These methods may mutate and depend on the state of the object argument,
 /// but may not depend on or mutate any other state. An exception is thrown
 /// if the object is null, but otherwise they cannot throw or diverge.
 enum BuiltinMethod {
   /// Add an item to a native list.
   /// 
   /// Takes any number of arguments, each argument will be added to the
   /// list on the order given (as per the JS `push` method).
   /// 
   /// Compiles to `object.push(x1, ..., xN)`.
   Push,
 
   /// Remove and return the last item from a native list.
   /// 
   /// Takes no arguments.
   /// 
   /// Compiles to `object.pop()`.
   Pop,
 }