Fix cue rendering test and include support for left/right alignment.

LayoutTests/media/track/captions-webvtt/captions-snap-to-lines-not-set.vtt

Index: LayoutTests/media/track/captions-webvtt/captions-snap-to-lines-not-set.vtt
diff --git a/LayoutTests/media/track/captions-webvtt/captions-snap-to-lines-not-set.vtt b/LayoutTests/media/track/captions-webvtt/captions-snap-to-lines-not-set.vtt
index edf7aa5e3e7a6ac0e85d8bcafb0ee365f4215689..0abadb47e3bd9b2f3adac470eb71236a316bc22c 100644
--- a/LayoutTests/media/track/captions-webvtt/captions-snap-to-lines-not-set.vtt
+++ b/LayoutTests/media/track/captions-webvtt/captions-snap-to-lines-not-set.vtt
@@ -1,7 +1,7 @@
 WEBVTT FILE
 
 1
-00:00:00.000 --> 00:00:00.500
+00:00:00.000 --> 00:00:00.500 line:100% position:50%
 This is a demo track to illustrate positioning features of cues.
 
 2
@@ -9,19 +9,19 @@ This is a demo track to illustrate positioning features of cues.
 Using HTML5 captions, you can position the cues anywhere.
 
 3
-00:00:01.000 --> 00:00:01.500 line:0% position:0%
+00:00:01.000 --> 00:00:01.500 line:0% position:0% align:start
 For example, here is a cue on the top left-corner.
 
 4
-00:00:01.500 --> 00:00:02.000 line:0% position:100%
+00:00:01.500 --> 00:00:02.000 line:0% position:100% align:end
 Or on the top-right corner.
 
 5
-00:00:02.000 --> 00:00:02.500 line:100% position:100%
+00:00:02.000 --> 00:00:02.500 line:100% position:100% align:right
 Bottom-right corner.
 
 6
-00:00:02.500 --> 00:00:03.000 line:100% position:0%
+00:00:02.500 --> 00:00:03.000 line:100% position:0% align:left
 And, as you might expect, the bottom-left one.
 
 7
@@ -29,7 +29,7 @@ And, as you might expect, the bottom-left one.
 Cues are implicitly displayed within the viewport area.
 
 8
-00:00:03.500 --> 00:00:04.000 line:100% position:50%
+00:00:03.500 --> 00:00:04.000 line:100% position:50% align:middle
 And always on top of the controls, if these are visible.
 
 9
@@ -37,11 +37,11 @@ And always on top of the controls, if these are visible.
 You may even have multiple cues in the same time.
 
 10
-00:00:04.000 --> 00:00:05.000 line:0% position:0%
+00:00:04.000 --> 00:00:05.000 line:0% position:0% align:start
 Top-left cue.
 
 11
-00:00:04.000 --> 00:00:05.000 line:0% position:100%
+00:00:04.000 --> 00:00:05.000 line:0% position:100% align:end
 Top-right cue.
 
 12
@@ -49,13 +49,13 @@ Top-right cue.
 Bottom cue.
 
 13
-00:00:04.000 --> 00:00:05.000 line:25% position:100%
+00:00:04.000 --> 00:00:05.000 line:25% position:100% align:end
 Random cue 1.
 
 14
-00:00:04.000 --> 00:00:05.000 line:33% position:44%
+00:00:04.000 --> 00:00:05.000 line:33% position:44% align:start
 Random cue 2.
 
 15
-00:00:04.000 --> 00:00:05.000 line:55% position:23%
+00:00:04.000 --> 00:00:05.000 line:55% position:23% align:start
 Random cue 3.