clang-format: Support case ranges.

Before (note the missing space before "..." which can lead to compile
errors):
  switch (x) {
    case 'A'... 'Z':
    case 1... 5:
        break;
  }

After:
  switch (x) {
    case 'A' ... 'Z':
    case 1 ... 5:
        break;
  }

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@193050 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/unittests/Format/FormatTest.cpp b/unittests/Format/FormatTest.cpp
index dcb708e..ad1cf75 100644
--- a/unittests/Format/FormatTest.cpp
+++ b/unittests/Format/FormatTest.cpp
@@ -590,6 +590,14 @@
                "});");
 }
 
+TEST_F(FormatTest, CaseRanges) {
+  verifyFormat("switch (x) {\n"
+               "case 'A' ... 'Z':\n"
+               "case 1 ... 5:\n"
+               "  break;\n"
+               "}");
+}
+
 TEST_F(FormatTest, FormatsLabels) {
   verifyFormat("void f() {\n"
                "  some_code();\n"