Flesh out dynamic invocation code

test/codegen/expect/dart/_interceptors.js

 var _interceptors;
 (function(exports) {
   'use strict';
   // Function _symbolToString: (Symbol) → String
   function _symbolToString(symbol) {
     return _internal.Symbol.getName(dart.as(symbol, _internal.Symbol));
   }
   // Function _symbolMapToStringMap: (Map<Symbol, dynamic>) → dynamic
   function _symbolMapToStringMap(map) {
     if (map === null)
@@ skipping 880 matching lines @@
       return this['&'](1) === 1;
     }
     toUnsigned(width) {
       return this['&']((1 << dart.notNull(width)) - 1);
     }
     toSigned(width) {
       let signMask = 1 << dart.notNull(width) - 1;
       return dart.notNull(this['&'](dart.notNull(signMask) - 1)) - dart.notNull(this['&'](signMask));
     }
     get bitLength() {
-      let nonneg = this['<'](0) ? dart.notNull(dart.throw_("Unimplemented PrefixExpression: -this")) - 1 : this;
+      let nonneg = this['<'](0) ? dart.notNull(this['unary-']()) - 1 : this;
       if (dart.notNull(nonneg) >= 4294967296) {
         nonneg = (dart.notNull(nonneg) / 4294967296).truncate();
         return dart.notNull(_bitCount(_spread(nonneg))) + 32;
       }
       return _bitCount(_spread(nonneg));
     }
     static [_bitCount](i) {
       i = dart.as(dart.dbinary(_shru(i, 0), '-', dart.dbinary(_shru(i, 1), '&', 1431655765)), core.int);
       i = (dart.notNull(i) & 858993459)['+'](dart.dbinary(_shru(i, 2), '&', 858993459));
       i = 252645135 & i['+'](_shru(i, 4));
@@ skipping 498 matching lines @@
   exports.JSExtendableArray = JSExtendableArray;
   exports.JSExtendableArray$ = JSExtendableArray$;
   exports.JSNumber = JSNumber;
   exports.JSInt = JSInt;
   exports.JSDouble = JSDouble;
   exports.JSPositiveInt = JSPositiveInt;
   exports.JSUInt32 = JSUInt32;
   exports.JSUInt31 = JSUInt31;
   exports.JSString = JSString;
 })(_interceptors || (_interceptors = {}));