fix some errors in our SDK, mostly around numbers

lib/runtime/dart/collection.js

 dart_library.library('dart/collection', null, /* Imports */[
   "dart_runtime/dart",
   'dart/core'
 ], /* Lazy imports */[
   'dart/_internal',
   'dart/_js_helper',
   'dart/math'
 ], function(exports, dart, core, _internal, _js_helper, math) {
   'use strict';
   let dartx = dart.dartx;
@@ skipping 4353 matching lines @@
           this[_keys] = null;
           return value;
         } else {
           return null;
         }
       }
       static _isStringKey(key) {
         return typeof key == 'string' && !dart.equals(key, '__proto__');
       }
       static _isNumericKey(key) {
-        return dart.is(key, core.num) && (key & 0x3ffffff) === key;
+        return typeof key == 'number' && (key & 0x3ffffff) === key;
       }
       [_computeHashCode](key) {
         return dart.hashCode(key) & 0x3ffffff;
       }
       static _hasTableEntry(table, key) {
         let entry = table[key];
         return entry != null;
       }
       static _getTableEntry(table, key) {
         let entry = table[key];
@@ skipping 466 matching lines @@
         } else {
           next[_previous] = previous;
         }
         this[_length] = dart.notNull(this[_length]) - 1;
         this[_modified]();
       }
       static _isStringKey(key) {
         return typeof key == 'string' && !dart.equals(key, '__proto__');
       }
       static _isNumericKey(key) {
-        return dart.is(key, core.num) && (key & 0x3ffffff) === key;
+        return typeof key == 'number' && (key & 0x3ffffff) === key;
       }
       [_computeHashCode](key) {
         return dart.hashCode(key) & 0x3ffffff;
       }
       static _getTableEntry(table, key) {
         return table[key];
       }
       static _setTableEntry(table, key, value) {
         dart.assert(value != null);
         table[key] = value;
@@ skipping 424 matching lines @@
           this[_elements] = null;
           return true;
         } else {
           return false;
         }
       }
       static _isStringElement(element) {
         return typeof element == 'string' && !dart.equals(element, '__proto__');
       }
       static _isNumericElement(element) {
-        return dart.is(element, core.num) && (element & 0x3ffffff) === element;
+        return typeof element == 'number' && (element & 0x3ffffff) === element;
       }
       [_computeHashCode](element) {
         return dart.hashCode(element) & 0x3ffffff;
       }
       static _hasTableEntry(table, key) {
         let entry = table[key];
         return entry != null;
       }
       static _setTableEntry(table, key, value) {
         dart.assert(value != null);
@@ skipping 415 matching lines @@
         } else {
           next[_previous] = previous;
         }
         this[_length] = dart.notNull(this[_length]) - 1;
         this[_modified]();
       }
       static _isStringElement(element) {
         return typeof element == 'string' && !dart.equals(element, '__proto__');
       }
       static _isNumericElement(element) {
-        return dart.is(element, core.num) && (element & 0x3ffffff) === element;
+        return typeof element == 'number' && (element & 0x3ffffff) === element;
       }
       [_computeHashCode](element) {
         return dart.hashCode(element) & 0x3ffffff;
       }
       static _getTableEntry(table, key) {
         return table[key];
       }
       static _setTableEntry(table, key, value) {
         dart.assert(value != null);
         table[key] = value;
@@ skipping 276 matching lines @@
   exports.LinkedHashMapKeyIterable$ = LinkedHashMapKeyIterable$;
   exports.LinkedHashMapKeyIterable = LinkedHashMapKeyIterable;
   exports.LinkedHashMapKeyIterator$ = LinkedHashMapKeyIterator$;
   exports.LinkedHashMapKeyIterator = LinkedHashMapKeyIterator;
   exports.HashSetIterator$ = HashSetIterator$;
   exports.HashSetIterator = HashSetIterator;
   exports.LinkedHashSetCell = LinkedHashSetCell;
   exports.LinkedHashSetIterator$ = LinkedHashSetIterator$;
   exports.LinkedHashSetIterator = LinkedHashSetIterator;
 });