Remove some low-value, slow tests (#4874)

The removed tests use real stubs and/or run Python and thus are pretty
slow to run. Most of them either test stubs in straightforward ways
(which is not very useful, since the coverage is bound to be spotty)
or some very basic functionality (which is covered by other tests).

The removals speed up the Python evaluation suite by about 25% on my
laptop (there is a high variance, though). There are probably others
that could safely be removed but I tried to be pretty conservative here.

test-data/unit/python2eval.test

@@ -109,13 +109,6 @@ f(re.match('x*', 'xxy'))
 [out]
 xx
 
-[case testVariableLengthTuple_python2]
-from typing import Tuple, cast
-x = cast(Tuple[int, ...], ())
-print(x)
-[out]
-()
-
 [case testFromFuturePrintFunction_python2]
 from __future__ import print_function
 print('a', 'b')
@@ -162,15 +155,13 @@ _program.py:5: error: Argument 1 to "f" has incompatible type "unicode"; expecte
 _program.py:6: error: Argument 1 to "f" has incompatible type "unicode"; expected "str"
 
 [case testStrUnicodeCompatibility_python2]
-import typing
 def f(s): # type: (unicode) -> None
     pass
 f(u'')
 f('')
 [out]
 
 [case testStrUnicodeCompatibilityInBuiltins_python2]
-import typing
 'x'.count('x')
 'x'.count(u'x')
 [out]
@@ -184,16 +175,6 @@ f(tuple())
 [out]
 ()
 
-[case testReadOnlyProperty_python2]
-import typing
-class A:
-    @property
-    def foo(self): # type: () -> int
-        return 1
-print(A().foo + 2)
-[out]
-3
-
 [case testIOTypes_python2]
 from typing import IO, TextIO, BinaryIO, Any
 class X(IO[str]): pass
@@ -259,19 +240,6 @@ print 'ok'
 [out]
 ok
 
-[case testUnionType_python2]
-from typing import Union
-y = None  # type: Union[int, str]
-def f(x): # type: (Union[int, str]) -> str
-    if isinstance(x, int):
-        x = str(x)
-    return x
-print f(12)
-print f('ab')
-[out]
-12
-ab
-
 [case testStrAdd_python2]
 import typing
 s = ''
@@ -294,21 +262,13 @@ s = ''.join([u''])  # Error
 _program.py:5: error: Incompatible types in assignment (expression has type "str", variable has type "int")
 _program.py:6: error: Incompatible types in assignment (expression has type "unicode", variable has type "str")
 
-[case testNamedTuple_python2]
-import typing
-from collections import namedtuple
-X = namedtuple('X', ['a', 'b'])
-x = X(a=1, b='s')
-print x.a, x.b
-[out]
-1 s
-
 [case testNamedTupleError_python2]
 import typing
 from collections import namedtuple
 X = namedtuple('X', ['a', 'b'])
 x = X(a=1, b='s')
 x.c
+x.a
 [out]
 _program.py:5: error: "X" has no attribute "c"
 
@@ -332,27 +292,6 @@ print 4j / 2.0
 6j
 2j
 
-[case testNamedTupleWithTypes_python2]
-from typing import NamedTuple
-N = NamedTuple('N', [('a', int), ('b', str)])
-n = N(1, 'x')
-print n
-a, b = n
-print a, b
-print n[0]
-[out]
-N(a=1, b='x')
-1 x
-1
-
-[case testUnionTypeAlias_python2]
-from typing import Union
-U = Union[int, str]
-u = 1 # type: U
-u = 1.1
-[out]
-_program.py:4: error: Incompatible types in assignment (expression has type "float", variable has type "Union[int, str]")
-
 [case testSuperNew_python2]
 from typing import Dict, Any
 class MyType(type):
@@ -365,24 +304,6 @@ print(type(A()).__name__)
 [out]
 Ax
 
-[case testSequenceIndexAndCount_python2]
-from typing import Sequence
-def f(x): # type: (Sequence[int]) -> None
-    print(x.index(1))
-    print(x.count(1))
-f([0, 0, 1, 1, 1])
-[out]
-2
-3
-
-[case testOptional_python2]
-from typing import Optional
-def f(): # type: () -> Optional[int]
-    pass
-x = f()
-y = 1
-y = x
-
 [case testUnicodeAndOverloading_python2]
 from m import f
 f(1)