Make fixed-width elements not center by default.

sky/tests/layout/ellipsis-expected.txt

Index: sky/tests/layout/ellipsis-expected.txt
diff --git a/sky/tests/layout/ellipsis-expected.txt b/sky/tests/layout/ellipsis-expected.txt
index 5d3ada6bfa5ec028c87c4ba9c4f101541bd18eba..5efb8354b0acb64fa97aa903390e4831682fd7cc 100644
--- a/sky/tests/layout/ellipsis-expected.txt
+++ b/sky/tests/layout/ellipsis-expected.txt
@@ -2,20 +2,20 @@ layer at (0,0) size 800x600
   RenderView {#document} at (0,0) size 800x600
 layer at (0,0) size 800x94
   RenderBlock {sky} at (0,0) size 800x94
-layer at (372,0) size 56x69 clip at (375,3) size 50x63 scrollWidth 93
-  RenderBlock {div} at (372,0) size 56x69 [border: (3px solid #0000FF)]
+layer at (0,0) size 56x69 clip at (3,3) size 50x63 scrollWidth 93
+  RenderBlock {div} at (0,0) size 56x69 [border: (3px solid #0000FF)]
     RenderBlock (anonymous) at (3,3) size 50x19
       RenderText {#text} at (0,0) size 91x19
         text run at (0,0) width 91: "These lines"
     RenderBlock (anonymous) at (3,47) size 50x19
       RenderText {#text} at (0,0) size 94x19
         text run at (0,0) width 94: "all ellipsize."
-layer at (375,22) size 56x25 backgroundClip at (375,22) size 50x25 clip at (378,25) size 47x19 outlineClip at (375,3) size 50x63 scrollWidth 53
+layer at (3,22) size 56x25 backgroundClip at (3,22) size 50x25 clip at (6,25) size 47x19 outlineClip at (3,3) size 50x63 scrollWidth 53
   RenderBlock {p} at (3,22) size 56x25 [border: (3px solid #FF0000)]
     RenderText {#text} at (3,3) size 54x19
       text run at (3,3) width 54: "should"
-layer at (372,69) size 56x25 clip at (375,72) size 50x19 scrollWidth 117
-  RenderBlock {p} at (372,69) size 56x25 [border: (3px solid #FF0000)]
+layer at (0,69) size 56x25 clip at (3,72) size 50x19 scrollWidth 117
+  RenderBlock {p} at (0,69) size 56x25 [border: (3px solid #FF0000)]
     RenderInline {span} at (0,0) size 117x19
       RenderText {#text} at (3,3) size 117x19
         text run at (3,3) width 117: "As should this."