Revert of Remove RegExp.multiline accessors.

test/mjsunit/regexp-static.js

Index: test/mjsunit/regexp-static.js
diff --git a/test/mjsunit/regexp-static.js b/test/mjsunit/regexp-static.js
index 0d6d85c66009b4746bace293127e53d6d7c7557d..62e4e7e3bd76a40a63b0434b61b4a397b53d2bf4 100644
--- a/test/mjsunit/regexp-static.js
+++ b/test/mjsunit/regexp-static.js
@@ -144,6 +144,8 @@
   assertEquals("", RegExp['$' + (i)], "$" + i);
 }
 
+RegExp.multiline = "foo";
+assertTrue(typeof RegExp.multiline == typeof Boolean(), "RegExp.multiline coerces values to booleans");
 RegExp.input = Number();
 assertTrue(typeof RegExp.input == typeof String(), "RegExp.input coerces values to booleans");