[Test] Add a few more + operands to a type checker perf test to exhibit

exponential behavior.

Binding value types early allows the previous version of this test
to compile, but the performance still doesn't scale with a few more
operands in the + chain.

Author: hborla

validation-test/Sema/type_checker_perf/fast/rdar46713933_literal_arg.swift renamed to validation-test/Sema/type_checker_perf/slow/rdar46713933_literal_arg.swift

@@ -7,5 +7,6 @@ func wrap<T: ExpressibleByFloatLiteral>(_ key: String, _ value: T) -> T { return
 func wrap<T: ExpressibleByStringLiteral>(_ key: String, _ value: T) -> T { return value }
 
 func wrapped() -> Int {
-  return wrap("1", 1) + wrap("1", 1) + wrap("1", 1) + wrap("1", 1)
+  return wrap("1", 1) + wrap("1", 1) + wrap("1", 1) + wrap("1", 1) + wrap("1", 1) + wrap("1", 1)
+  // expected-error@-1 {{the compiler is unable to type-check this expression in reasonable time}}
 }