preserve case when inline_script (#2991)

fixes #2989

test/compress/issue-2989.js

@@ -0,0 +1,21 @@
+inline_script_off: {
+    beautify = {
+        inline_script: false,
+    }
+    input: {
+        console.log("</sCrIpT>");
+    }
+    expect_exact: 'console.log("</sCrIpT>");'
+    expect_stdout: "</sCrIpT>"
+}
+
+inline_script_on: {
+    beautify = {
+        inline_script: true,
+    }
+    input: {
+        console.log("</sCrIpT>");
+    }
+    expect_exact: 'console.log("<\\/sCrIpT>");'
+    expect_stdout: "</sCrIpT>"
+}