SI-8630 lineToString no longer long by one at eof

One more EOL crasher, or lack-of-EOL crasher, when the text
is at EOF.

It was not caught by the last round of excellent and
thorough tests because

```
// If non-whitespace tokens run all the way up to EOF,
// positions go wrong because the correct end of the last
// token cannot be used as an index into the char array.
// The least painful way to address this was to add a
// newline to the array.
```

1 files changed, 5 insertions, 0 deletions

diff --git a/test/junit/scala/reflect/internal/util/SourceFileTest.scala b/test/junit/scala/reflect/internal/util/SourceFileTest.scala
index 903e705ba2..cad23eba14 100644
--- a/test/junit/scala/reflect/internal/util/SourceFileTest.scala
+++ b/test/junit/scala/reflect/internal/util/SourceFileTest.scala
@@ -17,6 +17,11 @@ class SourceFileTest {
     assertFalse(file.isEndOfLine(Int.MaxValue))
   }
 
+  @Test def si8630_lineToString(): Unit = {
+    val code = "abc "
+    assertEquals(code, new BatchSourceFile("", code).lineToString(0))
+  }
+
   @Test
   def si8205_lineToString(): Unit = {
     assertEquals("", lineContentOf("", 0))