Support for "a is Function".

tests/language/language-leg.status

 # Copyright (c) 2012, 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.
 
 [ $component == leg && $checked ]
 *: Skip
 
 
 [ $component == leg ]
 AdjacentStringLiteralsTest: Crash # Cannot call 'get:dartString' on "${s}".
 Constructor6Test: Crash
 CompileTimeConstant8Test: Fail # We don't take the generic type into account yet.
 CompileTimeConstantBTest: Fail # We don't handle constant map literals with __proto__ key yet.
 
 
 # Compilation errors.
 BreakTest: Fail # SsaBuilder for loop with aborting body not implemented
 CTConst3Test: Fail # CompileTimeConstantEvaluator not implemented
 CTConstTest: Fail # map not implemented
 CallOperatorTest: Fail # Unexpected token 'call'
-CallThroughGetterTest: Fail # Internal Error: Cannot find value
 CanonicalConstTest: Fail # map not implemented
 CharEscapeTest: Fail # Unhandled non-BMP character: U+10000
 ConstInitTest: Fail # CompileTimeConstantHandler with arguments not implemented
 ConstObjectsAreImmutableTest: Fail # map not implemented
 Constructor5Test: Fail # no matching constructor found
 ConstructorRedirectTest: Fail # staticFun(x, y) is only available in instance methods
 Context2Test: Fail # switch cases are not implemented
 ContinueTest: Fail # switch cases are not implemented
 DefaultFactoryLibraryTest: Fail # lib is not a type
 DefaultInitTest: Fail # CompileTimeConstantHandler with fields not implemented
 DisablePrivacyTest: Skip  # Issue 1882: Needs --disable_privacy support.
 DoWhileTest: Fail # SsaBuilder for loop with aborting body not implemented
 DoubleToStringAsExponentialTest: Fail # -0.0 is printed as 0.0.
 DoubleToStringAsFixedTest: Fail # -0.0 is printed as 0.0.
 DoubleToStringAsPrecisionTest: Fail # -0.0 is printed as 0.0.
 DynamicTest: Fail # cannot resolve type F1
 EmptyBlockCaseTest: Fail # switch cases are not implemented
 Factory3Test: Fail # Handling of compile-time constants.
 FinalSyntaxTest/none: Fail # Incorrect compile-time constant handling.
 ForTest: Fail # SsaBuilder for loop without condition not implemented
-FunctionSyntaxTest: Fail # Internal Error: Cannot find value
 FunctionTypeAlias2Test: Fail # cannot resolve type f1
 FunctionTypeAlias3Test: Fail # cannot resolve type F
 FunctionTypeAlias4Test: Fail # cannot resolve type F
 FunctionTypeAliasTest: Fail # cannot resolve type Fun
 FunctionTypeParameter2Test: Fail # Internal Error: expected expected optional parameters
 FunctionTypeParameterTest: Fail # Internal Error: expected expected optional parameters
 GenericInstanceofTest: Fail # cannot resolve type T
 GenericTest: Fail # cannot resolve type T
 GetSetSyntaxTest/none: Fail # Parsing of pseudo keywords.
 GettersSettersTest: Fail # Internal Error: SsaBuilder.visitIdentifier on non-this
@@ skipping 51 matching lines @@
 FunctionTest: Fail # continue not implemented
 GenericDeepTest: Fail # Expect.isTrue(false) fails.
 GenericInheritanceTest: Fail # Expect.isTrue(false) fails.
 GenericParameterizedExtendsTest: Fail # Expect.isTrue(false) fails.
 ImpliedInterfaceTest: Fail # Expect.equals(expected: <true>, actual: <false>) fails.
 InstanceCompoundAssignmentOperatorTest: Fail # Expect.equals(expected: <4>, actual: <5>) fails.
 Instanceof2Test: Fail # Expect.equals(expected: <true>, actual: <false>) fails.
 ListLiteral3Test: Fail # Expect.equals(expected: <true>, actual: <false>) fails.
 ListLiteral4Test: Fail # Expect.equals(expected: <110111>, actual: <null>) fails.
 ListTest: Fail # TypeError: Object ,,, has no method 'copyFrom$4'
-LocalFunction3Test: Fail # Expect.equals(expected: <Closure>, actual: <Instance of 'Closure'>) fails.
 Private3Test: Fail # Expect.equals(expected: <-1>, actual: <The Ring>) fails.
 PrivateTest: Fail # Expect.equals(expected: <99>, actual: <499>) fails.
 ToStringAsFixedTest: Fail # Expect.equals(expected: <0.0000006>, actual: <0.0000010>) fails.
 TypeChecksInFactoryMethodTest: Fail # Expect.equals(expected: <true>, actual: <false>) fails.
 TypedMessageTest: Fail # SyntaxError: Unexpected token this
 
 
 #
 # The following tests are all semantic tests that we can rely on dartc
 # catching for now.
@@ skipping 150 matching lines @@
 ClosureBreakTest: Fail
 ExecuteFinally3Test: Fail
 ExecuteFinally9Test: Fail
 
 
 [ $component == leg && $mode == release ]
 AssignTopMethodNegativeTest: Crash
 
 [ $component == legium ]
 *: Skip