Add a new implementation of HashMap that uses JS objects for its (multiple) hash tables.

runtime/vm/vm.gypi

 # Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
 {
   'variables': {
     'builtin_in_cc_file': '../bin/builtin_in.cc',
     'async_cc_file': '<(SHARED_INTERMEDIATE_DIR)/async_gen.cc',
     'async_patch_cc_file': '<(SHARED_INTERMEDIATE_DIR)/async_patch_gen.cc',
     'corelib_cc_file': '<(SHARED_INTERMEDIATE_DIR)/corelib_gen.cc',
     'corelib_patch_cc_file': '<(SHARED_INTERMEDIATE_DIR)/corelib_patch_gen.cc',
     'collection_cc_file': '<(SHARED_INTERMEDIATE_DIR)/collection_gen.cc',
+    'collection_patch_cc_file': '<(SHARED_INTERMEDIATE_DIR)/collection_patch_gen.cc',
     'collection_dev_cc_file': '<(SHARED_INTERMEDIATE_DIR)/collection_dev_gen.cc',
     'crypto_cc_file': '<(SHARED_INTERMEDIATE_DIR)/crypto_gen.cc',
     'math_cc_file': '<(SHARED_INTERMEDIATE_DIR)/math_gen.cc',
     'math_patch_cc_file': '<(SHARED_INTERMEDIATE_DIR)/math_patch_gen.cc',
     'mirrors_cc_file': '<(SHARED_INTERMEDIATE_DIR)/mirrors_gen.cc',
     'mirrors_patch_cc_file': '<(SHARED_INTERMEDIATE_DIR)/mirrors_patch_gen.cc',
     'isolate_cc_file': '<(SHARED_INTERMEDIATE_DIR)/isolate_gen.cc',
     'isolate_patch_cc_file': '<(SHARED_INTERMEDIATE_DIR)/isolate_patch_gen.cc',
     'json_cc_file': '<(SHARED_INTERMEDIATE_DIR)/json_gen.cc',
     'json_patch_cc_file': '<(SHARED_INTERMEDIATE_DIR)/json_patch_gen.cc',
@@ skipping 67 matching lines @@
     },
     {
       'target_name': 'libdart_lib_withcore',
       'type': 'static_library',
       'dependencies': [
         'generate_async_cc_file',
         'generate_async_patch_cc_file',
         'generate_corelib_cc_file',
         'generate_corelib_patch_cc_file',
         'generate_collection_cc_file',
+        'generate_collection_patch_cc_file',
         'generate_collection_dev_cc_file',
         'generate_crypto_cc_file',
         'generate_math_cc_file',
         'generate_math_patch_cc_file',
         'generate_isolate_cc_file',
         'generate_isolate_patch_cc_file',
         'generate_json_cc_file',
         'generate_json_patch_cc_file',
         'generate_mirrors_cc_file',
         'generate_mirrors_patch_cc_file',
         'generate_scalarlist_cc_file',
         'generate_scalarlist_patch_cc_file',
         'generate_typeddata_cc_file',
         'generate_typeddata_patch_cc_file',
         'generate_uri_cc_file',
         'generate_utf_cc_file',
       ],
       'includes': [
         '../lib/async_sources.gypi',
+        '../lib/collection_sources.gypi',
         '../lib/lib_sources.gypi',
         '../lib/isolate_sources.gypi',
         '../lib/math_sources.gypi',
         '../lib/mirrors_sources.gypi',
         '../lib/scalarlist_sources.gypi',
         '../lib/typeddata_sources.gypi',
       ],
       'sources': [
         'bootstrap.cc',
         # Include generated source files.
         '<(async_cc_file)',
         '<(async_patch_cc_file)',
         '<(corelib_cc_file)',
         '<(corelib_patch_cc_file)',
         '<(collection_cc_file)',
+        '<(collection_patch_cc_file)',
         '<(collection_dev_cc_file)',
         '<(crypto_cc_file)',
         '<(math_cc_file)',
         '<(math_patch_cc_file)',
         '<(isolate_cc_file)',
         '<(isolate_patch_cc_file)',
         '<(json_cc_file)',
         '<(json_patch_cc_file)',
         '<(mirrors_cc_file)',
         '<(mirrors_patch_cc_file)',
         '<(scalarlist_cc_file)',
         '<(scalarlist_patch_cc_file)',
         '<(typeddata_cc_file)',
         '<(typeddata_patch_cc_file)',
         '<(uri_cc_file)',
         '<(utf_cc_file)',
       ],
       'include_dirs': [
         '..',
       ],
     },
     {
       'target_name': 'libdart_lib',
       'type': 'static_library',
       'includes': [
         '../lib/async_sources.gypi',
+        '../lib/collection_sources.gypi',
         '../lib/lib_sources.gypi',
         '../lib/isolate_sources.gypi',
         '../lib/math_sources.gypi',
         '../lib/mirrors_sources.gypi',
         '../lib/scalarlist_sources.gypi',
         '../lib/typeddata_sources.gypi',
       ],
       'sources': [
         'bootstrap_nocorelib.cc',
       ],
@@ skipping 594 matching lines @@
             '--input_cc', '<(builtin_in_cc_file)',
             '--include', 'vm/bootstrap.h',
             '--var_name', 'dart::Bootstrap::async_patch_',
             '<@(_sources)',
           ],
           'message': 'Generating ''<(async_patch_cc_file)'' file.'
         },
       ]
     },
     {
+      'target_name': 'generate_collection_patch_cc_file',
+      'type': 'none',
+      'includes': [
+        # Load the runtime implementation sources.
+        '../lib/collection_sources.gypi',
+      ],
+      'sources/': [
+        # Exclude all .[cc|h] files.
+        # This is only here for reference. Excludes happen after
+        # variable expansion, so the script has to do its own
+        # exclude processing of the sources being passed.
+        ['exclude', '\\.cc|h$'],
+      ],
+      'actions': [
+        {
+          'action_name': 'generate_collection_patch_cc',
+          'inputs': [
+            '../tools/create_string_literal.py',
+            '<(builtin_in_cc_file)',
+            '<@(_sources)',
+          ],
+          'outputs': [
+            '<(collection_patch_cc_file)',
+          ],
+          'action': [
+            'python',
+            'tools/create_string_literal.py',
+            '--output', '<(collection_patch_cc_file)',
+            '--input_cc', '<(builtin_in_cc_file)',
+            '--include', 'vm/bootstrap.h',
+            '--var_name', 'dart::Bootstrap::collection_patch_',
+            '<@(_sources)',
+          ],
+          'message': 'Generating ''<(collection_patch_cc_file)'' file.'
+        },
+      ]
+    },
+    {
       'target_name': 'generate_isolate_patch_cc_file',
       'type': 'none',
       'includes': [
         # Load the runtime implementation sources.
         '../lib/isolate_sources.gypi',
       ],
       'sources/': [
         # Exclude all .[cc|h] files.
         # This is only here for reference. Excludes happen after
         # variable expansion, so the script has to do its own
@@ skipping 424 matching lines @@
             '--include', 'INTENTIONALLY_LEFT_BLANK',
             '--var_name', 'INTENTIONALLY_LEFT_BLANK_TOO',
             '<(snapshot_test_dart_file)',
           ],
           'message': 'Generating ''<(snapshot_test_dat_file)'' file.'
         },
       ]
     },
   ]
 }