LibJS: Inline fast case for Value::to_{boolean,number,numeric,primitive}

These functions all have a very common case that can be dealt with a
very simple inline check, often avoiding the need to call an out-of-line
function. This patch moves the common case to inline functions in a new
ValueInlines.h header (necessary due to header dependency issues..)

8% speed-up on the entire Kraken benchmark :^)

Userland/Libraries/LibJS/Runtime/Intl/NumberFormat.cpp

@@ -15,6 +15,7 @@
 #include <LibJS/Runtime/Intl/NumberFormat.h>
 #include <LibJS/Runtime/Intl/NumberFormatFunction.h>
 #include <LibJS/Runtime/Intl/PluralRules.h>
+#include <LibJS/Runtime/ValueInlines.h>
 #include <LibUnicode/CurrencyCode.h>
 #include <math.h>
 #include <stdlib.h>