CLJS-807: Emitter cannot emit BigInt or BigDecimal

Extend compiler to emit double-approximations of BigInt and BigDecimal so
that literal forms like "1N" or "1.5M" can compile.

src/clj/cljs/compiler.clj

@@ -167,6 +167,8 @@
 (defmethod emit-constant Long [x] (emits "(" x ")"))
 (defmethod emit-constant Integer [x] (emits x)) ; reader puts Integers in metadata
 (defmethod emit-constant Double [x] (emits x))
+(defmethod emit-constant BigDecimal [x] (emits (.doubleValue ^BigDecimal x)))
+(defmethod emit-constant clojure.lang.BigInt [x] (emits (.doubleValue ^clojure.lang.BigInt x)))
 (defmethod emit-constant String [x]
   (emits (wrap-in-double-quotes (escape-string x))))
 (defmethod emit-constant Boolean [x] (emits (if x "true" "false")))

test/cljs/cljs/core_test.cljs

@@ -2460,5 +2460,11 @@
 
   (assert (= {:foo true} (meta ^:foo (fn []))))
 
+  ;; CLJS-807
+  (assert (= -1 -1N))
+  (assert (= 9.007199254740996E15 9007199254740995N))
+  (assert (= 1.5 1.5M))
+  (assert (= 4.9E-324 5E-324M))
+
   :ok
   )