Convert fast/multicol/float-avoidance to reftest.

LayoutTests/platform/mac/fast/multicol/vertical-rl/float-avoidance-expected.txt

Index: LayoutTests/platform/mac/fast/multicol/vertical-rl/float-avoidance-expected.txt
diff --git a/LayoutTests/platform/mac/fast/multicol/vertical-rl/float-avoidance-expected.txt b/LayoutTests/platform/mac/fast/multicol/vertical-rl/float-avoidance-expected.txt
deleted file mode 100644
index 73cccc206279e44545aea8ea528beaa0307302ad..0000000000000000000000000000000000000000
--- a/LayoutTests/platform/mac/fast/multicol/vertical-rl/float-avoidance-expected.txt
+++ /dev/null
@@ -1,18 +0,0 @@
-layer at (0,0) size 800x600
-  RenderView at (0,0) size 800x600
-layer at (0,0) size 800x600
-  RenderBlock {HTML} at (0,0) size 800x600
-    RenderBody {BODY} at (8,8) size 784x584
-      RenderBlock (floating) {DIV} at (0,0) size 100x200 [bgcolor=#00FF00]
-layer at (560,8) size 132x435
-  RenderBlock {DIV} at (100,0) size 132x435 [border: (10px solid #000000)]
-    RenderBlock {P} at (26,10) size 80x415
-      RenderText {#text} at (0,0) size 80x415
-        text run at (0,0) width 415: "This technology preview of our award winning next generation"
-        text run at (16,0) width 57: "browser "
-        text run at (16,56) width 359: "is a sign of things to come from Mozilla. Powerful yet"
-        text run at (32,0) width 121: "easy to use. This "
-        text run at (32,120) width 295: "maintenance release provides a few updates"
-        text run at (48,0) width 246: "based on user feedback - including "
-        text run at (48,245) width 169: "changes to the Extension"
-        text run at (64,0) width 206: "System and icon improvements."