DevTools: allow injecting CSS rules without breaking styles sidebar.

LayoutTests/inspector-protocol/css/cssom-matching-rules-expected.txt

Index: LayoutTests/inspector-protocol/css/cssom-matching-rules-expected.txt
diff --git a/LayoutTests/inspector-protocol/css/cssom-matching-rules-expected.txt b/LayoutTests/inspector-protocol/css/cssom-matching-rules-expected.txt
new file mode 100644
index 0000000000000000000000000000000000000000..8e45e42b41039e9fbedab6f12dde405a12c48f9e
--- /dev/null
+++ b/LayoutTests/inspector-protocol/css/cssom-matching-rules-expected.txt
@@ -0,0 +1,179 @@
+The test verifies CSS.getMatchedStylesForNode when used concurrently with the CSSOM modifications.
+
+
+Running test: testModifyRule
+--------------
+Original rule:
+*#modifyRule* {    regular
+    box-sizing: border-box;
+}
+*#modifyRule* {    regular
+    height: 100%;
+}
+*#modifyRule* {    regular
+    width: 100%;
+}
+--------------
+Modified rule 1:
+*#modifyrule* {    regular    readonly
+    box-sizing: border-box;
+    color: red;
+}
+*#modifyRule* {    regular
+    height: 100%;
+}
+*#modifyRule* {    regular
+    width: 100%;
+}
+---------------
+Modified rule 3:
+*#modifyrule* {    regular    readonly
+    box-sizing: border-box;
+    color: red;
+}
+*#modifyRule* {    regular
+    height: 100%;
+}
+*#modifyrule* {    regular    readonly
+    width: 100%;
+    color: blue;
+}
+---------------
+Modified rule 2:
+*#modifyrule* {    regular    readonly
+    box-sizing: border-box;
+    color: red;
+}
+*#modifyrule* {    regular    readonly
+    height: 100%;
+    color: green;
+}
+*#modifyrule* {    regular    readonly
+    width: 100%;
+    color: blue;
+}
+---------------
+Restored rule 2:
+*#modifyrule* {    regular    readonly
+    box-sizing: border-box;
+    color: red;
+}
+*#modifyRule* {    regular
+    height: 100%;
+}
+*#modifyrule* {    regular    readonly
+    width: 100%;
+    color: blue;
+}
+-----------------
+Restored rule 1,3:
+*#modifyRule* {    regular
+    box-sizing: border-box;
+}
+*#modifyRule* {    regular
+    height: 100%;
+}
+*#modifyRule* {    regular
+    width: 100%;
+}
+
+Running test: testInsertFirstRule
+Original rule:
+*#insertRule* {    regular
+    box-sizing: border-box;
+}
+*#insertRule* {    regular
+    width: 100%;
+}
+--------------
+After inserted rule:
+*#insertrule* {    regular    readonly
+    color: red;
+}
+*#insertRule* {    regular
+    box-sizing: border-box;
+}
+*#insertRule* {    regular
+    width: 100%;
+}
+--------------
+Restored rule:
+*#insertRule* {    regular
+    box-sizing: border-box;
+}
+*#insertRule* {    regular
+    width: 100%;
+}
+
+Running test: testInsertMiddleRule
+Original rule:
+*#insertRule* {    regular
+    box-sizing: border-box;
+}
+*#insertRule* {    regular
+    width: 100%;
+}
+--------------
+After inserted rule:
+*#insertRule* {    regular
+    box-sizing: border-box;
+}
+*#insertrule* {    regular    readonly
+    color: red;
+}
+*#insertRule* {    regular
+    width: 100%;
+}
+--------------
+Restored rule:
+*#insertRule* {    regular
+    box-sizing: border-box;
+}
+*#insertRule* {    regular
+    width: 100%;
+}
+
+Running test: testInsertLastRule
+Original rule:
+*#insertRule* {    regular
+    box-sizing: border-box;
+}
+*#insertRule* {    regular
+    width: 100%;
+}
+--------------
+After inserted rule:
+*#insertRule* {    regular
+    box-sizing: border-box;
+}
+*#insertRule* {    regular
+    width: 100%;
+}
+*#insertrule* {    regular    readonly
+    color: red;
+}
+--------------
+Restored rule:
+*#insertRule* {    regular
+    box-sizing: border-box;
+}
+*#insertRule* {    regular
+    width: 100%;
+}
+
+Running test: testRemoveRule
+Original rule:
+*#removeRule* {    regular
+    box-sizing: border-box;
+}
+*#removeRule* {    regular
+    width: 100%;
+}
+-------------------
+After remove rule 1:
+*#removeRule* {    regular
+    width: 100%;
+}
+-------------------
+After remove rule 2:
+