clang-format: Improve selective comment formatting.

Starting here:
  int x; // Format this line only.
  int xx; //
  int xxxxx; //

Before:
  int x;     // Format this line only.
  int xx; //
  int xxxxx; //

After:
  int x;  // Format this line only.
  int xx; //
  int xxxxx; //

llvm-svn: 257258
diff --git a/clang/unittests/Format/FormatTestSelective.cpp b/clang/unittests/Format/FormatTestSelective.cpp
index d53d1c0..699600c 100644
--- a/clang/unittests/Format/FormatTestSelective.cpp
+++ b/clang/unittests/Format/FormatTestSelective.cpp
@@ -162,6 +162,13 @@
                    "// This is\n"
                    "// not formatted.   ",
                    0, 0));
+  EXPECT_EQ("int x;  // Format this line.\n"
+            "int xx; //\n"
+            "int xxxxx; //",
+            format("int x; // Format this line.\n"
+                   "int xx; //\n"
+                   "int xxxxx; //",
+                   0, 0));
 }
 
 TEST_F(FormatTestSelective, IndividualStatementsOfNestedBlocks) {