DevTools: [Elements] Implement "Copy CSS Path" context menu item for elements

LayoutTests/inspector/elements/elements-css-path-expected.txt

Index: LayoutTests/inspector/elements/elements-css-path-expected.txt
diff --git a/LayoutTests/inspector/elements/elements-css-path-expected.txt b/LayoutTests/inspector/elements/elements-css-path-expected.txt
new file mode 100644
index 0000000000000000000000000000000000000000..0c525ce1b9bb42b558c8d0b3316a7b9d44c6e7e4
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+++ b/LayoutTests/inspector/elements/elements-css-path-expected.txt
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+Tests DOMNode.cssPath()
+
+First
+Second
+1
+2
+3
+4
+5
+6
+7
+8
+9
+10
+11 ид
+12
+
+13
+14
+15
+16
+17
+18
+19
+20
+21 класс
+22
+23
+  html
+    head
+      head > meta
+      #script-id
+      head > script:nth-child(3)
+      #test-script
+    body
+      body > p
+      body > article:nth-child(2)
+      body > article:nth-child(3)
+      #ids
+        #ids > div:nth-child(1)
+        #ids > div:nth-child(2)
+        #inner-id
+        #\23 \22 ridiculous\22 \2e id
+        #\27 quoted\2e value\27
+        #\2e foo\2e bar
+        #\2d
+        #-a
+        #\2d 0
+        #\37
+        #ид
+        #ids > p
+      #classes
+        #classes > div.bar
+        #classes > div:nth-child(2)
+        #classes > div.\2e foo
+        #classes > div.\2e foo\2e bar
+        #classes > div.\2d
+        #classes > div.-a
+        #classes > div.\2d 0
+        #classes > div.\37
+        #classes > div.класс
+        #classes > span
+        #id-with-class
+