Fix accessibility coordinates within iframes.

content/test/data/accessibility/iframe-coordinates-expected-mac.txt

Index: content/test/data/accessibility/iframe-coordinates-expected-mac.txt
diff --git a/content/test/data/accessibility/iframe-coordinates-expected-mac.txt b/content/test/data/accessibility/iframe-coordinates-expected-mac.txt
new file mode 100644
index 0000000000000000000000000000000000000000..813df00d83b6689611df3895b631d48aeb0e1a7d
--- /dev/null
+++ b/content/test/data/accessibility/iframe-coordinates-expected-mac.txt
@@ -0,0 +1,19 @@
+AXWebArea position=(0, 0) size=(800, 600) scroll=(0, 0)
+    AXGroup position=(0, 0) size=(300, 100)
+        AXButton position=(20, 20) size=(260, 60)
+    AXGroup position=(0, 100) size=(300, 100)
+        AXButton position=(20, 120) size=(260, 60)
+    AXGroup position=(0, 200) size=(800, 104)

[aboxhall, 2013/01/29 01:52:40]

Where are these 4px coming from?

[dmazzoni, 2013/01/29 16:51:50]

Borders, margins, and padding, oh my!
Borders, margins, and padding, oh my!

If I fix this, the html won't fit in 80 columns without splitting things into
style declarations in the header. I'm just not sure which is more or less
readable, round numbers in the expectations or more compact html.

[aboxhall, 2013/01/29 17:43:26]

Ok - I was just confused because it looked like you'd set borders, margin and
padding all to zero at some point. I think it probably would be easier to put a
style block in the header to keep all the numbers round - I really did have to
spend quite a long time (although it didn't help that I was on the bus and kept
getting distracted) trying to make sure everything added up.

[dmazzoni, 2013/01/29 18:51:25]

Seems reasonable. I fixed it to use nice, round numbers.

+        AXUnknown position=(0, 200) size=(300, 100)
+            AXUnknown position=(0, 0) size=(0, 0)
+                AXWebArea position=(0, 200) size=(300, 100) scroll=(0, 0)
+                    AXGroup position=(0, 200) size=(300, 100)
+                        AXButton position=(20, 220) size=(260, 60)
+    AXGroup position=(0, 304) size=(800, 54)
+        AXUnknown position=(0, 304) size=(150, 50)
+            AXUnknown position=(0, 0) size=(0, 0)
+                AXWebArea position=(0, 304) size=(300, 100) scroll=(150, 50)

[aboxhall, 2013/01/29 19:53:47]

Where did the scroll coordinates go?

[dmazzoni, 2013/01/29 21:02:07]

Oh, that was left over from my own internal debugging. Those aren't actually
exposed in the native API in a straightforward way so it doesn't make sense to
include them here. Maybe we can expose those on the AXScrollBars at some point,
but either way that's outside of the scope of this change.

+                    AXGroup position=(-150, 254) size=(300, 100)
+                        AXButton position=(-130, 274) size=(260, 60)
+                AXScrollBar position=(0, 0) size=(0, 0)
+                AXScrollBar position=(0, 0) size=(0, 0)