CSP: Deduplicate violation reports before sending.

LayoutTests/http/tests/security/contentSecurityPolicy/report-multiple-violations-02-expected.txt

Index: LayoutTests/http/tests/security/contentSecurityPolicy/report-multiple-violations-02-expected.txt
diff --git a/LayoutTests/http/tests/security/contentSecurityPolicy/report-multiple-violations-02-expected.txt b/LayoutTests/http/tests/security/contentSecurityPolicy/report-multiple-violations-02-expected.txt
new file mode 100644
index 0000000000000000000000000000000000000000..d1b56b6a8d18892fd47e7bd04ab45c71a8115771
--- /dev/null
+++ b/LayoutTests/http/tests/security/contentSecurityPolicy/report-multiple-violations-02-expected.txt
@@ -0,0 +1,12 @@
+CONSOLE MESSAGE: [Report Only] Refused to evaluate a string as JavaScript because 'unsafe-eval' is not an allowed source of script in the following Content Security Policy directive: "script-src 'unsafe-inline' 'self'".
+
+PingLoader dispatched to 'http://127.0.0.1:8000/security/contentSecurityPolicy/resources/does-not-exist'.
+CONSOLE MESSAGE: [Report Only] Refused to evaluate a string as JavaScript because 'unsafe-eval' is not an allowed source of script in the following Content Security Policy directive: "script-src 'unsafe-inline' 'self'".
+
+CONSOLE MESSAGE: [Report Only] Refused to evaluate a string as JavaScript because 'unsafe-eval' is not an allowed source of script in the following Content Security Policy directive: "script-src 'unsafe-inline' 'self'".
+
+CONSOLE MESSAGE: [Report Only] Refused to evaluate a string as JavaScript because 'unsafe-eval' is not an allowed source of script in the following Content Security Policy directive: "script-src 'unsafe-inline' 'self'".
+
+CONSOLE MESSAGE: [Report Only] Refused to evaluate a string as JavaScript because 'unsafe-eval' is not an allowed source of script in the following Content Security Policy directive: "script-src 'unsafe-inline' 'self'".
+
+This tests that multiple violations on a page trigger multiple reports if and only if the violations are distinct. This test passes if only one. PingLoader callback is visible in the output.