[Python3] Fix TestObjCMethods.py to work with py2 and 3.

git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@354286 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/packages/Python/lldbsuite/test/lang/objc/foundation/TestObjCMethods.py b/packages/Python/lldbsuite/test/lang/objc/foundation/TestObjCMethods.py
index 42535ca..dd53407 100644
--- a/packages/Python/lldbsuite/test/lang/objc/foundation/TestObjCMethods.py
+++ b/packages/Python/lldbsuite/test/lang/objc/foundation/TestObjCMethods.py
@@ -317,7 +317,7 @@
             lines = f.readlines()
             num_errors = 0
             for line in lines:
-                if string.find(line, "$__lldb") != -1:
+                if "$__lldb" in line:
                     if num_errors == 0:
                         print(
                             "error: found spurious name lookups when evaluating an expression:")