sdk files reorganization to make dart2js a proper package

sdk/lib/_internal/compiler/js_lib/js_rti.dart

Index: sdk/lib/_internal/compiler/js_lib/js_rti.dart
diff --git a/sdk/lib/_internal/compiler/js_lib/js_rti.dart b/sdk/lib/_internal/compiler/js_lib/js_rti.dart
deleted file mode 100644
index e5669e2a6babfca6dfcb3b2d8269714294549f74..0000000000000000000000000000000000000000
--- a/sdk/lib/_internal/compiler/js_lib/js_rti.dart
+++ /dev/null
@@ -1,681 +0,0 @@
-// Copyright (c) 2013, 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.
-
-/**
- * This part contains helpers for supporting runtime type information.
- *
- * The helper use a mixture of Dart and JavaScript objects. To indicate which is
- * used where we adopt the scheme of using explicit type annotation for Dart
- * objects and 'var' or omitted return type for JavaScript objects.
- *
- * Since bool, int, and String values are represented by the same JavaScript
- * primitives, type annotations are used for these types in all cases.
- *
- * Several methods use a common JavaScript encoding of runtime type information.
- * This encoding is referred to as the type representation which is one of
- * these:
- *  1) a JavaScript constructor for a class C: the represented type is the raw
- *     type C.
- *  2) a JavaScript array: the first entry is of type 1 and contains the
- *     subtyping flags and the substitution of the type and the rest of the
- *     array are the type arguments.
- *  3) `null`: the dynamic type.
- *  4) a JavaScript object representing the function type. For instance, it has
- *     the form  {ret: rti, args: [rti], opt: [rti], named: {name: rti}} for a
- *     function with a return type, regular, optional and named arguments.
- *
- * To check subtype relations between generic classes we use a JavaScript
- * expression that describes the necessary substitution for type arguments.
- * Such a substitution expresssion can be:
- *  1) `null`, if no substituted check is necessary, because the
- *     type variables are the same or there are no type variables in the class
- *     that is checked for.
- *  2) A list expression describing the type arguments to be used in the
- *     subtype check, if the type arguments to be used in the check do not
- *     depend on the type arguments of the object.
- *  3) A function mapping the type variables of the object to be checked to
- *     a list expression. The function may also return null, which is equivalent
- *     to an array containing only null values.
- */
-
-part of _js_helper;
-
-Type createRuntimeType(String name) => new TypeImpl(name);
-
-class TypeImpl implements Type {
-  final String _typeName;
-  String _unmangledName;
-
-  TypeImpl(this._typeName);
-
-  String toString() {
-    if (_unmangledName != null) return _unmangledName;
-    String unmangledName =
-        unmangleAllIdentifiersIfPreservedAnyways(_typeName);
-    return _unmangledName = unmangledName;
-  }
-
-  // TODO(ahe): This is a poor hashCode as it collides with its name.
-  int get hashCode => _typeName.hashCode;
-
-  bool operator ==(other) {
-    return  (other is TypeImpl) && _typeName == other._typeName;
-  }
-}
-
-/**
- * Represents a type variable.
- *
- * This class holds the information needed when reflecting on generic classes
- * and their members.
- */
-class TypeVariable {
-  final Type owner;
-  final String name;
-  final int bound;
-
-  const TypeVariable(this.owner, this.name, this.bound);
-}
-
-getMangledTypeName(TypeImpl type) => type._typeName;
-
-/**
- * Sets the runtime type information on [target]. [rti] is a type
- * representation of type 4 or 5, that is, either a JavaScript array or
- * `null`.
- */
-Object setRuntimeTypeInfo(Object target, var rti) {
-  assert(rti == null || isJsArray(rti));
-  // We have to check for null because factories may return null.
-  if (target != null) JS('var', r'#.$builtinTypeInfo = #', target, rti);
-  return target;
-}
-
-/**
- * Returns the runtime type information of [target]. The returned value is a
- * list of type representations for the type arguments.
- */
-getRuntimeTypeInfo(Object target) {
-  if (target == null) return null;
-  return JS('var', r'#.$builtinTypeInfo', target);
-}
-
-/**
- * Returns the type arguments of [target] as an instance of [substitutionName].
- */
-getRuntimeTypeArguments(target, substitutionName) {
-  var substitution = getField(target,
-      '${JS_GET_NAME(JsGetName.OPERATOR_AS_PREFIX)}$substitutionName');
-  return substitute(substitution, getRuntimeTypeInfo(target));
-}
-
-/**
- * Returns the [index]th type argument of [target] as an instance of
- * [substitutionName].
- */
-@NoThrows() @NoSideEffects() @NoInline()
-getRuntimeTypeArgument(Object target, String substitutionName, int index) {
-  var arguments = getRuntimeTypeArguments(target, substitutionName);
-  return arguments == null ? null : getIndex(arguments, index);
-}
-
-@NoThrows() @NoSideEffects() @NoInline()
-getTypeArgumentByIndex(Object target, int index) {
-  var rti = getRuntimeTypeInfo(target);
-  return rti == null ? null : getIndex(rti, index);
-}
-
-void copyTypeArguments(Object source, Object target) {
-  JS('var', r'#.$builtinTypeInfo = #.$builtinTypeInfo', target, source);
-}
-
-/**
- * Retrieves the class name from type information stored on the constructor
- * of [object].
- */
-String getClassName(var object) {
-  return rawRtiToJsConstructorName(getRawRuntimeType(getInterceptor(object)));
-}
-
-/**
- * Creates the string representation for the type representation [rti]
- * of type 4, the JavaScript array, where the first element represents the class
- * and the remaining elements represent the type arguments.
- */
-String getRuntimeTypeAsString(var rti, {String onTypeVariable(int i)}) {
-  assert(isJsArray(rti));
-  String className = rawRtiToJsConstructorName(getIndex(rti, 0));
-  return '$className${joinArguments(rti, 1, onTypeVariable: onTypeVariable)}';
-}
-
-/**
- * Returns a human-readable representation of the type representation [rti].
- */
-String runtimeTypeToString(var rti, {String onTypeVariable(int i)}) {
-  if (rti == null) {
-    return 'dynamic';
-  } else if (isJsArray(rti)) {
-    // A list representing a type with arguments.
-    return getRuntimeTypeAsString(rti, onTypeVariable: onTypeVariable);
-  } else if (isJsFunction(rti)) {
-    // A reference to the constructor.
-    return rawRtiToJsConstructorName(rti);
-  } else if (rti is int) {
-    if (onTypeVariable == null) {
-      return rti.toString();
-    } else {
-      return onTypeVariable(rti);
-    }
-  } else {
-    // TODO(ahe): Handle function types, and be sure to always return a string.
-    return null;
-  }
-}
-
-/**
- * Creates a comma-separated string of human-readable representations of the
- * type representations in the JavaScript array [types] starting at index
- * [startIndex].
- */
-String joinArguments(var types, int startIndex,
-                     {String onTypeVariable(int i)}) {
-  if (types == null) return '';
-  assert(isJsArray(types));
-  bool firstArgument = true;
-  bool allDynamic = true;
-  StringBuffer buffer = new StringBuffer();
-  for (int index = startIndex; index < getLength(types); index++) {
-    if (firstArgument) {
-      firstArgument = false;
-    } else {
-      buffer.write(', ');
-    }
-    var argument = getIndex(types, index);
-    if (argument != null) {
-      allDynamic = false;
-    }
-    buffer.write(runtimeTypeToString(argument, onTypeVariable: onTypeVariable));
-  }
-  return allDynamic ? '' : '<$buffer>';
-}
-
-/**
- * Returns a human-readable representation of the type of [object].
- *
- * In minified mode does *not* use unminified identifiers (even when present).
- */
-String getRuntimeTypeString(var object) {
-  String className = getClassName(object);
-  if (object == null) return className;
-  var rti = JS('var', r'#.$builtinTypeInfo', object);
-  return "$className${joinArguments(rti, 0)}";
-}
-
-Type getRuntimeType(var object) {
-  String type = getRuntimeTypeString(object);
-  return new TypeImpl(type);
-}
-
-/**
- * Applies the [substitution] on the [arguments].
- *
- * See the comment in the beginning of this file for a description of the
- * possible values for [substitution].
- */
-substitute(var substitution, var arguments) {
-  assert(substitution == null ||
-         isJsFunction(substitution));
-  assert(arguments == null || isJsArray(arguments));
-  if (isJsFunction(substitution)) {
-    substitution = invoke(substitution, arguments);
-    if (substitution == null || isJsArray(substitution)) {
-      arguments = substitution;
-    } else if (isJsFunction(substitution)) {
-      // TODO(johnniwinther): Check if this is still needed.
-      arguments = invoke(substitution, arguments);
-    }
-  }
-  return arguments;
-}
-
-/**
- * Perform a type check with arguments on the Dart object [object].
- *
- * Parameters:
- * - [isField]: the name of the flag/function to check if the object
- *   is of the correct class.
- * - [checks]: the (JavaScript) list of type representations for the
- *   arguments to check against.
- * - [asField]: the name of the function that transforms the type
- *   arguments of [objects] to an instance of the class that we check
- *   against.
- */
-bool checkSubtype(Object object, String isField, List checks, String asField) {
-  if (object == null) return false;
-  var arguments = getRuntimeTypeInfo(object);
-  // Interceptor is needed for JSArray and native classes.
-  // TODO(sra): It could be a more specialized interceptor since [object] is not
-  // `null` or a primitive.
-  // TODO(9586): Move type info for static functions onto an interceptor.
-  var interceptor = getInterceptor(object);
-  var isSubclass = getField(interceptor, isField);
-  // When we read the field and it is not there, [isSubclass] will be `null`.
-  if (isSubclass == null) return false;
-  // Should the asField function be passed the receiver?
-  var substitution = getField(interceptor, asField);
-  return checkArguments(substitution, arguments, checks);
-}
-
-/// Returns the field's type name.
-///
-/// In minified mode, uses the unminified names if available.
-String computeTypeName(String isField, List arguments) {
-  // Extract the class name from the is field and append the textual
-  // representation of the type arguments.
-  return Primitives.formatType(isCheckPropertyToJsConstructorName(isField),
-                               arguments);
-}
-
-Object subtypeCast(Object object, String isField, List checks, String asField) {
-  if (object != null && !checkSubtype(object, isField, checks, asField)) {
-    String actualType = Primitives.objectTypeName(object);
-    String typeName = computeTypeName(isField, checks);
-    // TODO(johnniwinther): Move type lookup to [CastErrorImplementation] to
-    // align with [TypeErrorImplementation].
-    throw new CastErrorImplementation(actualType, typeName);
-  }
-  return object;
-}
-
-Object assertSubtype(Object object, String isField, List checks,
-                     String asField) {
-  if (object != null && !checkSubtype(object, isField, checks, asField)) {
-    String typeName = computeTypeName(isField, checks);
-    throw new TypeErrorImplementation(object, typeName);
-  }
-  return object;
-}
-
-/// Checks that the type represented by [subtype] is a subtype of [supertype].
-/// If not a type error with [message] is thrown.
-assertIsSubtype(var subtype, var supertype, String message) {
-  if (!isSubtype(subtype, supertype)) {
-    throwTypeError(message);
-  }
-}
-
-throwTypeError(message) {
-  throw new TypeErrorImplementation.fromMessage(message);
-}
-
-/**
- * Check that the types in the list [arguments] are subtypes of the types in
- * list [checks] (at the respective positions), possibly applying [substitution]
- * to the arguments before the check.
- *
- * See the comment in the beginning of this file for a description of the
- * possible values for [substitution].
- */
-bool checkArguments(var substitution, var arguments, var checks) {
-  return areSubtypes(substitute(substitution, arguments), checks);
-}
-
-/**
- * Checks whether the types of [s] are all subtypes of the types of [t].
- *
- * [s] and [t] are either `null` or JavaScript arrays of type representations,
- * A `null` argument is interpreted as the arguments of a raw type, that is a
- * list of `dynamic`. If [s] and [t] are JavaScript arrays they must be of the
- * same length.
- *
- * See the comment in the beginning of this file for a description of type
- * representations.
- */
-bool areSubtypes(var s, var t) {
-  // `null` means a raw type.
-  if (s == null || t == null) return true;
-
-  assert(isJsArray(s));
-  assert(isJsArray(t));
-  assert(getLength(s) == getLength(t));
-
-  int len = getLength(s);
-  for (int i = 0; i < len; i++) {
-    if (!isSubtype(getIndex(s, i), getIndex(t, i))) {
-      return false;
-    }
-  }
-  return true;
-}
-
-/**
- * Computes the signature by applying the type arguments of [context] as an
- * instance of [contextName] to the signature function [signature].
- */
-computeSignature(var signature, var context, var contextName) {
-  var typeArguments = getRuntimeTypeArguments(context, contextName);
-  return invokeOn(signature, context, typeArguments);
-}
-
-/**
- * Returns `true` if the runtime type representation [type] is a supertype of
- * [Null].
- */
-bool isSupertypeOfNull(var type) {
-  // `null` means `dynamic`.
-  return type == null || isDartObjectTypeRti(type) || isNullTypeRti(type);
-}
-
-/**
- * Tests whether the Dart object [o] is a subtype of the runtime type
- * representation [t].
- *
- * See the comment in the beginning of this file for a description of type
- * representations.
- */
-bool checkSubtypeOfRuntimeType(o, t) {
-  if (o == null) return isSupertypeOfNull(t);
-  if (t == null) return true;
-  // Get the runtime type information from the object here, because we may
-  // overwrite o with the interceptor below.
-  var rti = getRuntimeTypeInfo(o);
-  o = getInterceptor(o);
-  var type = getRawRuntimeType(o);
-  if (rti != null) {
-    // If the type has type variables (that is, `rti != null`), make a copy of
-    // the type arguments and insert [o] in the first position to create a
-    // compound type representation.
-    rti = JS('JSExtendableArray', '#.slice()', rti);  // Make a copy.
-    JS('', '#.splice(0, 0, #)', rti, type);  // Insert type at position 0.
-    type = rti;
-  }
-  if (isDartFunctionType(t)) {
-    // Functions are treated specially and have their type information stored
-    // directly in the instance.
-    var targetSignatureFunction =
-        getField(o, '${JS_GET_NAME(JsGetName.SIGNATURE_NAME)}');
-    if (targetSignatureFunction == null) return false;
-    type = invokeOn(targetSignatureFunction, o, null);
-    return isFunctionSubtype(type, t);
-  }
-  return isSubtype(type, t);
-}
-
-Object subtypeOfRuntimeTypeCast(Object object, var type) {
-  if (object != null && !checkSubtypeOfRuntimeType(object, type)) {
-    String actualType = Primitives.objectTypeName(object);
-    throw new CastErrorImplementation(actualType, runtimeTypeToString(type));
-  }
-  return object;
-}
-
-Object assertSubtypeOfRuntimeType(Object object, var type) {
-  if (object != null && !checkSubtypeOfRuntimeType(object, type)) {
-    throw new TypeErrorImplementation(object, runtimeTypeToString(type));
-  }
-  return object;
-}
-
-/**
- * Extracts the type arguments from a type representation. The result is a
- * JavaScript array or `null`.
- */
-getArguments(var type) {
-  return isJsArray(type) ? JS('var', r'#.slice(1)', type) : null;
-}
-
-/**
- * Checks whether the type represented by the type representation [s] is a
- * subtype of the type represented by the type representation [t].
- *
- * See the comment in the beginning of this file for a description of type
- * representations.
- *
- * The arguments [s] and [t] must be types, usually represented by the
- * constructor of the class, or an array (for generic types).
- */
-bool isSubtype(var s, var t) {
-  // Subtyping is reflexive.
-  if (isIdentical(s, t)) return true;
-  // If either type is dynamic, [s] is a subtype of [t].
-  if (s == null || t == null) return true;
-  if (isDartFunctionType(t)) {
-    return isFunctionSubtype(s, t);
-  }
-  // Check function types against the Function class.
-  if (isDartFunctionType(s)) {
-    return isDartFunctionTypeRti(t);
-  }
-
-  // Get the object describing the class and check for the subtyping flag
-  // constructed from the type of [t].
-  var typeOfS = isJsArray(s) ? getIndex(s, 0) : s;
-  var typeOfT = isJsArray(t) ? getIndex(t, 0) : t;
-
-  // Check for a subtyping flag.
-  // Get the necessary substitution of the type arguments, if there is one.
-  var substitution;
-  if (isNotIdentical(typeOfT, typeOfS)) {
-    if (!builtinIsSubtype(typeOfS, runtimeTypeToString(typeOfT))) {
-      return false;
-    }
-    var typeOfSPrototype = JS('', '#.prototype', typeOfS);
-    var field = '${JS_GET_NAME(JsGetName.OPERATOR_AS_PREFIX)}'
-        '${runtimeTypeToString(typeOfT)}';
-    substitution = getField(typeOfSPrototype, field);
-  }
-  // The class of [s] is a subclass of the class of [t].  If [s] has no type
-  // arguments and no substitution, it is used as raw type.  If [t] has no
-  // type arguments, it used as a raw type.  In both cases, [s] is a subtype
-  // of [t].
-  if ((!isJsArray(s) && substitution == null) || !isJsArray(t)) {
-    return true;
-  }
-  // Recursively check the type arguments.
-  return checkArguments(substitution, getArguments(s), getArguments(t));
-}
-
-bool isAssignable(var s, var t) {
-  return isSubtype(s, t) || isSubtype(t, s);
-}
-
-/**
- * If [allowShorter] is `true`, [t] is allowed to be shorter than [s].
- */
-bool areAssignable(List s, List t, bool allowShorter) {
-  // Both lists are empty and thus equal.
-  if (t ==null && s == null) return true;
-  // [t] is empty (and [s] is not) => only OK if [allowShorter].
-  if (t == null) return allowShorter;
-  // [s] is empty (and [t] is not) => [s] is not longer or equal to [t].
-  if (s == null) return false;
-
-  assert(isJsArray(s));
-  assert(isJsArray(t));
-
-  int sLength = getLength(s);
-  int tLength = getLength(t);
-  if (allowShorter) {
-    if (sLength < tLength) return false;
-  } else {
-    if (sLength != tLength) return false;
-  }
-
-  for (int i = 0; i < tLength; i++) {
-    if (!isAssignable(getIndex(s, i), getIndex(t, i))) {
-      return false;
-    }
-  }
-  return true;
-}
-
-bool areAssignableMaps(var s, var t) {
-  if (t == null) return true;
-  if (s == null) return false;
-
-  assert(isJsObject(s));
-  assert(isJsObject(t));
-
-  List names =
-      JSArray.markFixedList(JS('', 'Object.getOwnPropertyNames(#)', t));
-  for (int i = 0; i < names.length; i++) {
-    var name = names[i];
-    if (JS('bool', '!Object.hasOwnProperty.call(#, #)', s, name)) {
-      return false;
-    }
-    var tType = JS('', '#[#]', t, name);
-    var sType = JS('', '#[#]', s, name);
-    if (!isAssignable(tType, sType)) return false;
-  }
-  return true;
-}
-
-bool isFunctionSubtype(var s, var t) {
-  assert(isDartFunctionType(t));
-  if (!isDartFunctionType(s)) return false;
-  var voidReturnTag = JS_GET_NAME(JsGetName.FUNCTION_TYPE_VOID_RETURN_TAG);
-  var returnTypeTag = JS_GET_NAME(JsGetName.FUNCTION_TYPE_RETURN_TYPE_TAG);
-  if (hasField(s, voidReturnTag)) {
-    if (hasNoField(t, voidReturnTag) && hasField(t, returnTypeTag)) {
-      return false;
-    }
-  } else if (hasNoField(t, voidReturnTag)) {
-    var sReturnType = getField(s, returnTypeTag);
-    var tReturnType = getField(t, returnTypeTag);
-    if (!isAssignable(sReturnType, tReturnType)) return false;
-  }
-  var requiredParametersTag =
-      JS_GET_NAME(JsGetName.FUNCTION_TYPE_REQUIRED_PARAMETERS_TAG);
-  var sParameterTypes = getField(s, requiredParametersTag);
-  var tParameterTypes = getField(t, requiredParametersTag);
-
-  var optionalParametersTag =
-      JS_GET_NAME(JsGetName.FUNCTION_TYPE_OPTIONAL_PARAMETERS_TAG);
-  var sOptionalParameterTypes = getField(s, optionalParametersTag);
-  var tOptionalParameterTypes = getField(t, optionalParametersTag);
-
-  int sParametersLen = sParameterTypes != null ? getLength(sParameterTypes) : 0;
-  int tParametersLen = tParameterTypes != null ? getLength(tParameterTypes) : 0;
-
-  int sOptionalParametersLen =
-      sOptionalParameterTypes != null ? getLength(sOptionalParameterTypes) : 0;
-  int tOptionalParametersLen =
-      tOptionalParameterTypes != null ? getLength(tOptionalParameterTypes) : 0;
-
-  if (sParametersLen > tParametersLen) {
-    // Too many required parameters in [s].
-    return false;
-  }
-  if (sParametersLen + sOptionalParametersLen <
-      tParametersLen + tOptionalParametersLen) {
-    // Too few required and optional parameters in [s].
-    return false;
-  }
-  if (sParametersLen == tParametersLen) {
-    // Simple case: Same number of required parameters.
-    if (!areAssignable(sParameterTypes, tParameterTypes, false)) return false;
-    if (!areAssignable(sOptionalParameterTypes,
-                       tOptionalParameterTypes, true)) {
-      return false;
-    }
-  } else {
-    // Complex case: Optional parameters of [s] for required parameters of [t].
-    int pos = 0;
-    // Check all required parameters of [s].
-    for (; pos < sParametersLen; pos++) {
-      if (!isAssignable(getIndex(sParameterTypes, pos),
-                        getIndex(tParameterTypes, pos))) {
-        return false;
-      }
-    }
-    int sPos = 0;
-    int tPos = pos;
-    // Check the remaining parameters of [t] with the first optional parameters
-    // of [s].
-    for (; tPos < tParametersLen ; sPos++, tPos++) {
-      if (!isAssignable(getIndex(sOptionalParameterTypes, sPos),
-                        getIndex(tParameterTypes, tPos))) {
-        return false;
-      }
-    }
-    tPos = 0;
-    // Check the optional parameters of [t] with the remaining optional
-    // parameters of [s]:
-    for (; tPos < tOptionalParametersLen ; sPos++, tPos++) {
-      if (!isAssignable(getIndex(sOptionalParameterTypes, sPos),
-                        getIndex(tOptionalParameterTypes, tPos))) {
-        return false;
-      }
-    }
-  }
-
-  var namedParametersTag =
-      JS_GET_NAME(JsGetName.FUNCTION_TYPE_NAMED_PARAMETERS_TAG);
-  var sNamedParameters = getField(s, namedParametersTag);
-  var tNamedParameters = getField(t, namedParametersTag);
-  return areAssignableMaps(sNamedParameters, tNamedParameters);
-}
-
-/**
- * Calls the JavaScript [function] with the [arguments] with the global scope
- * as the `this` context.
- */
-invoke(var function, var arguments) => invokeOn(function, null, arguments);
-
-/**
- * Calls the JavaScript [function] with the [arguments] with [receiver] as the
- * `this` context.
- */
-Object invokeOn(function, receiver, arguments) {
-  assert(isJsFunction(function));
-  assert(arguments == null || isJsArray(arguments));
-  return JS('var', r'#.apply(#, #)', function, receiver, arguments);
-}
-
-/// Calls the property [name] on the JavaScript [object].
-call(var object, String name) => JS('var', r'#[#]()', object, name);
-
-/// Returns the property [name] of the JavaScript object [object].
-getField(var object, String name) => JS('var', r'#[#]', object, name);
-
-/// Returns the property [index] of the JavaScript array [array].
-getIndex(var array, int index) {
-  assert(isJsArray(array));
-  return JS('var', r'#[#]', array, index);
-}
-
-/// Returns the length of the JavaScript array [array].
-int getLength(var array) {
-  assert(isJsArray(array));
-  return JS('int', r'#.length', array);
-}
-
-/// Returns whether [value] is a JavaScript array.
-bool isJsArray(var value) {
-  return value is JSArray;
-}
-
-hasField(var object, var name) => JS('bool', r'# in #', name, object);
-
-hasNoField(var object, var name) => !hasField(object, name);
-
-/// Returns `true` if [o] is a JavaScript function.
-bool isJsFunction(var o) => JS('bool', r'typeof # == "function"', o);
-
-/// Returns `true` if [o] is a JavaScript object.
-bool isJsObject(var o) => JS('bool', r"typeof # == 'object'", o);
-
-/**
- * Returns `true` if the JavaScript values [s] and [t] are identical. We use
- * this helper instead of [identical] because `identical` needs to merge
- * `null` and `undefined` (which we can avoid).
- */
-bool isIdentical(var s, var t) => JS('bool', '# === #', s, t);
-
-/**
- * Returns `true` if the JavaScript values [s] and [t] are not identical. We use
- * this helper instead of [identical] because `identical` needs to merge
- * `null` and `undefined` (which we can avoid).
- */
-bool isNotIdentical(var s, var t) => JS('bool', '# !== #', s, t);