Reverse style resolution to avoid N^2 walk when building the render tree

LayoutTests/editing/style/typing-style-003-expected.txt

Index: LayoutTests/editing/style/typing-style-003-expected.txt
diff --git a/LayoutTests/editing/style/typing-style-003-expected.txt b/LayoutTests/editing/style/typing-style-003-expected.txt
index 73cdc661a4715d632dfb38e2e91807a7e6085195..16216e61e3331079fa300979d244bd59c14a39c1 100644
--- a/LayoutTests/editing/style/typing-style-003-expected.txt
+++ b/LayoutTests/editing/style/typing-style-003-expected.txt
@@ -52,21 +52,21 @@ EDITING DELEGATE: webViewDidChangeSelection:WebViewDidChangeSelectionNotificatio
 EDITING DELEGATE: webViewDidChange:WebViewDidChangeNotification
 xxxxxxxxxxxxxxx
 execTypeCharacterCommand: x <span id="test"></span>
-execTypeCharacterCommand: xx<span id="test"></span>
-execTypeCharacterCommand: xxx<span id="test"></span>
-execBoldCommand: xxx<span id="test"></span>
-execTypeCharacterCommand: xxx<b>x</b><span id="test"></span>
-execTypeCharacterCommand: xxx<b>xx</b><span id="test"></span>
-execTypeCharacterCommand: xxx<b>xxx</b><span id="test"></span>
-execItalicCommand: xxx<b>xxx</b><span id="test"></span>
-execTypeCharacterCommand: xxx<b>xxx<i>x</i></b><span id="test"></span>
-execTypeCharacterCommand: xxx<b>xxx<i>xx</i></b><span id="test"></span>
-execTypeCharacterCommand: xxx<b>xxx<i>xxx</i></b><span id="test"></span>
-execBoldCommand: xxx<b>xxx<i>xxx</i></b><span id="test"></span>
-execTypeCharacterCommand: xxx<b>xxx</b><i><b>xxx</b>x</i><span id="test"></span>
-execTypeCharacterCommand: xxx<b>xxx</b><i><b>xxx</b>xx</i><span id="test"></span>
-execTypeCharacterCommand: xxx<b>xxx</b><i><b>xxx</b>xxx</i><span id="test"></span>
-execItalicCommand: xxx<b>xxx</b><i><b>xxx</b>xxx</i><span id="test"></span>
-execTypeCharacterCommand: xxx<b>xxx</b><i><b>xxx</b>xxx</i>x<span id="test"></span>
-execTypeCharacterCommand: xxx<b>xxx</b><i><b>xxx</b>xxx</i>xx<span id="test"></span>
-execTypeCharacterCommand: xxx<b>xxx</b><i><b>xxx</b>xxx</i>xxx<span id="test"></span>
+execTypeCharacterCommand: xx <span id="test"></span>
+execTypeCharacterCommand: xxx <span id="test"></span>
+execBoldCommand: xxx <span id="test"></span>
+execTypeCharacterCommand: xxx<b>x</b> <span id="test"></span>
+execTypeCharacterCommand: xxx<b>xx</b> <span id="test"></span>
+execTypeCharacterCommand: xxx<b>xxx</b> <span id="test"></span>
+execItalicCommand: xxx<b>xxx</b> <span id="test"></span>
+execTypeCharacterCommand: xxx<b>xxx<i>x</i></b> <span id="test"></span>
+execTypeCharacterCommand: xxx<b>xxx<i>xx</i></b> <span id="test"></span>
+execTypeCharacterCommand: xxx<b>xxx<i>xxx</i></b> <span id="test"></span>
+execBoldCommand: xxx<b>xxx<i>xxx</i></b> <span id="test"></span>
+execTypeCharacterCommand: xxx<b>xxx</b><i><b>xxx</b>x</i> <span id="test"></span>
+execTypeCharacterCommand: xxx<b>xxx</b><i><b>xxx</b>xx</i> <span id="test"></span>
+execTypeCharacterCommand: xxx<b>xxx</b><i><b>xxx</b>xxx</i> <span id="test"></span>
+execItalicCommand: xxx<b>xxx</b><i><b>xxx</b>xxx</i> <span id="test"></span>
+execTypeCharacterCommand: xxx<b>xxx</b><i><b>xxx</b>xxx</i>x <span id="test"></span>
+execTypeCharacterCommand: xxx<b>xxx</b><i><b>xxx</b>xxx</i>xx <span id="test"></span>
+execTypeCharacterCommand: xxx<b>xxx</b><i><b>xxx</b>xxx</i>xxx <span id="test"></span>