Update XFAIL

The latest clang in our tree now passes the below four tests, so
remove their XFAIL:

    libc++ :: std/strings/string.view/string_view.literals/literal.pass.cpp
    libc++ :: std/strings/string.view/string_view.literals/literal1.pass.cpp
    libc++ :: std/strings/string.view/string_view.literals/literal2.pass.cpp
    libc++ :: std/strings/string.view/string_view.literals/literal3.pass.cpp

Bug: 36400049
Test: ./run_tests.py
Change-Id: I309d1eed2a04ab13165167ab2c0b3a8334014cbd
diff --git a/test/std/strings/string.view/string_view.literals/literal.pass.cpp b/test/std/strings/string.view/string_view.literals/literal.pass.cpp
index 23e9a75..710009c 100644
--- a/test/std/strings/string.view/string_view.literals/literal.pass.cpp
+++ b/test/std/strings/string.view/string_view.literals/literal.pass.cpp
@@ -12,10 +12,6 @@
 // UNSUPPORTED: clang-3.3, clang-3.4, clang-3.5, clang-3.6, clang-3.7, clang-3.8, clang-3.9
 // UNSUPPORTED: apple-clang-6, apple-clang-7, apple-clang-8
 // Note: libc++ supports string_view before C++17, but literals were introduced in C++14
-//
-// This will fail before r290744
-// http://b/36400049
-// XFAIL: *
 
 #include <string_view>
 #include <cassert>
diff --git a/test/std/strings/string.view/string_view.literals/literal1.pass.cpp b/test/std/strings/string.view/string_view.literals/literal1.pass.cpp
index 52e2306..f663d02 100644
--- a/test/std/strings/string.view/string_view.literals/literal1.pass.cpp
+++ b/test/std/strings/string.view/string_view.literals/literal1.pass.cpp
@@ -12,10 +12,6 @@
 // UNSUPPORTED: clang-3.3, clang-3.4, clang-3.5, clang-3.6, clang-3.7, clang-3.8, clang-3.9
 // UNSUPPORTED: apple-clang-6, apple-clang-7, apple-clang-8
 // Note: libc++ supports string_view before C++17, but literals were introduced in C++14
-//
-// This will fail before r290744
-// http://b/36400049
-// XFAIL: *
 
 #include <string_view>
 #include <cassert>
diff --git a/test/std/strings/string.view/string_view.literals/literal2.pass.cpp b/test/std/strings/string.view/string_view.literals/literal2.pass.cpp
index 0bd8605..3bb6f6c 100644
--- a/test/std/strings/string.view/string_view.literals/literal2.pass.cpp
+++ b/test/std/strings/string.view/string_view.literals/literal2.pass.cpp
@@ -12,10 +12,6 @@
 // UNSUPPORTED: clang-3.3, clang-3.4, clang-3.5, clang-3.6, clang-3.7, clang-3.8, clang-3.9
 // UNSUPPORTED: apple-clang-6, apple-clang-7, apple-clang-8
 // Note: libc++ supports string_view before C++17, but literals were introduced in C++14
-//
-// This will fail before r290744
-// http://b/36400049
-// XFAIL: *
 
 #include <string_view>
 #include <cassert>
diff --git a/test/std/strings/string.view/string_view.literals/literal3.pass.cpp b/test/std/strings/string.view/string_view.literals/literal3.pass.cpp
index b5e5ff0..144a1cd 100644
--- a/test/std/strings/string.view/string_view.literals/literal3.pass.cpp
+++ b/test/std/strings/string.view/string_view.literals/literal3.pass.cpp
@@ -12,10 +12,6 @@
 // UNSUPPORTED: clang-3.3, clang-3.4, clang-3.5, clang-3.6, clang-3.7, clang-3.8, clang-3.9
 // UNSUPPORTED: apple-clang-6, apple-clang-7, apple-clang-8
 // Note: libc++ supports string_view before C++17, but literals were introduced in C++14
-//
-// This will fail before r290744
-// http://b/36400049
-// XFAIL: *
 
 #include <string_view>
 #include <cassert>