Fix clang-format bug in unwrapped-line merging.

Before (in styles that allow it), clang-format would not merge an
if statement onto a single line, if only the second line was format
(e.g. in an editor integration):

if (a)
  return; // clang-format invoked on this line.

With this patch, this gets properly merged to:

if (a) return; // ...

llvm-svn: 181770
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index b7f544e..19c5215 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -245,6 +245,8 @@
                "}",
                AllowsMergedIf);
 
+  EXPECT_EQ("if (a) return;", format("if(a)\nreturn;", 7, 1, AllowsMergedIf));
+
   AllowsMergedIf.ColumnLimit = 14;
   verifyFormat("if (a) return;", AllowsMergedIf);
   verifyFormat("if (aaaaaaaaa)\n"
@@ -3810,7 +3812,7 @@
             "a;\n"
             "}\n"
             "{\n"
-            "  b;\n"
+            "  b; //\n"
             "}\n"
             "}",
             format("{\n"
@@ -3818,15 +3820,15 @@
                    "a;\n"
                    "}\n"
                    "{\n"
-                   "           b;\n"
+                   "           b; //\n"
                    "}\n"
                    "}",
                    22, 2, getLLVMStyle()));
   EXPECT_EQ("  {\n"
-            "    a;\n"
+            "    a; //\n"
             "  }",
             format("  {\n"
-                   "a;\n"
+                   "a; //\n"
                    "  }",
                    4, 2, getLLVMStyle()));
   EXPECT_EQ("void f() {}\n"