Fix ExtensionRegistry copying and add tests.

- Fix up -copyWithZone: to not leave the two registries sharing
  some of the storage by using -addExtensions:.
- Improve -addExtensions: to clone the sub dict when there is
  nothing to merge into.
- A ExtensionRegistry unittests.
- Update project schemes to not have extra things in perf scheme.

2 files changed, 15 insertions, 2 deletions

diff --git a/objectivec/ProtocolBuffers_OSX.xcodeproj/project.pbxproj b/objectivec/ProtocolBuffers_OSX.xcodeproj/project.pbxproj
index 919d0076..cd7fcc9e 100644
--- a/objectivec/ProtocolBuffers_OSX.xcodeproj/project.pbxproj
+++ b/objectivec/ProtocolBuffers_OSX.xcodeproj/project.pbxproj
@@ -52,6 +52,7 @@
 		F4487C751AADF7F500531423 /* GPBMessageTests+Runtime.m in Sources */ = {isa = PBXBuildFile; fileRef = F4487C741AADF7F500531423 /* GPBMessageTests+Runtime.m */; };
 		F4487C7F1AAF62CD00531423 /* GPBMessageTests+Serialization.m in Sources */ = {isa = PBXBuildFile; fileRef = F4487C7E1AAF62CD00531423 /* GPBMessageTests+Serialization.m */; };
 		F4487C831AAF6AB300531423 /* GPBMessageTests+Merge.m in Sources */ = {isa = PBXBuildFile; fileRef = F4487C821AAF6AB300531423 /* GPBMessageTests+Merge.m */; };
+		F4584D821ECCB52A00803AB6 /* GPBExtensionRegistryTest.m in Sources */ = {isa = PBXBuildFile; fileRef = F4584D7E1ECCB38900803AB6 /* GPBExtensionRegistryTest.m */; };
 		F45C69CC16DFD08D0081955B /* GPBExtensionInternals.m in Sources */ = {isa = PBXBuildFile; fileRef = F45C69CB16DFD08D0081955B /* GPBExtensionInternals.m */; };
 		F45E57C71AE6DC6A000B7D99 /* text_format_map_unittest_data.txt in Resources */ = {isa = PBXBuildFile; fileRef = F45E57C61AE6DC6A000B7D99 /* text_format_map_unittest_data.txt */; };
 		F47476E51D21A524007C7B1A /* Duration.pbobjc.m in Sources */ = {isa = PBXBuildFile; fileRef = 8B4248D41A92826400BC1EC6 /* Duration.pbobjc.m */; };
@@ -180,6 +181,7 @@
 		F4487C821AAF6AB300531423 /* GPBMessageTests+Merge.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = "GPBMessageTests+Merge.m"; sourceTree = "<group>"; };
 		F44929001C866B1900C2548A /* GPBCodedOutputStream_PackagePrivate.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = GPBCodedOutputStream_PackagePrivate.h; sourceTree = "<group>"; };
 		F451D3F51A8AAE8700B8A22C /* GPBProtocolBuffers_RuntimeSupport.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = GPBProtocolBuffers_RuntimeSupport.h; sourceTree = "<group>"; };
+		F4584D7E1ECCB38900803AB6 /* GPBExtensionRegistryTest.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = GPBExtensionRegistryTest.m; sourceTree = "<group>"; };
 		F45C69CB16DFD08D0081955B /* GPBExtensionInternals.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = GPBExtensionInternals.m; sourceTree = "<group>"; };
 		F45E57C61AE6DC6A000B7D99 /* text_format_map_unittest_data.txt */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text; path = text_format_map_unittest_data.txt; sourceTree = "<group>"; };
 		F4AC9E1D1A8BEB3500BD6E83 /* unittest_cycle.proto */ = {isa = PBXFileReference; lastKnownFileType = text; path = unittest_cycle.proto; sourceTree = "<group>"; };
@@ -403,6 +405,7 @@
 				F4353D301AC06F10005A6198 /* GPBDictionaryTests+String.m */,
 				F4353D311AC06F10005A6198 /* GPBDictionaryTests+UInt32.m */,
 				F4353D321AC06F10005A6198 /* GPBDictionaryTests+UInt64.m */,
+				F4584D7E1ECCB38900803AB6 /* GPBExtensionRegistryTest.m */,
 				7461B6A30F94FDF800A0C422 /* GPBMessageTests.m */,
 				F4487C821AAF6AB300531423 /* GPBMessageTests+Merge.m */,
 				F4487C741AADF7F500531423 /* GPBMessageTests+Runtime.m */,
@@ -418,8 +421,8 @@
 				7461B6BA0F94FDF900A0C422 /* GPBUtilitiesTests.m */,
 				8B4248DB1A92933A00BC1EC6 /* GPBWellKnownTypesTest.m */,
 				7461B6BC0F94FDF900A0C422 /* GPBWireFormatTests.m */,
-				F43C88CF191D77FC009E917D /* text_format_unittest_data.txt */,
 				F45E57C61AE6DC6A000B7D99 /* text_format_map_unittest_data.txt */,
+				F43C88CF191D77FC009E917D /* text_format_unittest_data.txt */,
 				8B7E6A7414893DBA00F8884A /* unittest_custom_options.proto */,
 				F4AC9E1D1A8BEB3500BD6E83 /* unittest_cycle.proto */,
 				8B7E6A7514893DBA00F8884A /* unittest_embed_optimize_for.proto */,
@@ -429,8 +432,8 @@
 				8BBD9DB016DD1DC8008E1EC1 /* unittest_lite.proto */,
 				8B7E6A7B14893DBC00F8884A /* unittest_mset.proto */,
 				8B7E6A7C14893DBC00F8884A /* unittest_no_generic_services.proto */,
-				8B09AAF614B663A7007B4184 /* unittest_objc.proto */,
 				F4CF31701B162ED800BD9B06 /* unittest_objc_startup.proto */,
+				8B09AAF614B663A7007B4184 /* unittest_objc.proto */,
 				8B7E6A7D14893DBC00F8884A /* unittest_optimize_for.proto */,
 				F4487C781AADFB3100531423 /* unittest_runtime_proto2.proto */,
 				F4487C791AADFB3200531423 /* unittest_runtime_proto3.proto */,
@@ -669,6 +672,7 @@
 				F4F8D8831D789FD9002CE128 /* GPBUnittestProtos2.m in Sources */,
 				F4353D1D1AB8822D005A6198 /* GPBDescriptorTests.m in Sources */,
 				8B4248BB1A8C256A00BC1EC6 /* GPBSwiftTests.swift in Sources */,
+				F4584D821ECCB52A00803AB6 /* GPBExtensionRegistryTest.m in Sources */,
 				5102DABC1891A073002037B6 /* GPBConcurrencyTests.m in Sources */,
 				F4487C751AADF7F500531423 /* GPBMessageTests+Runtime.m in Sources */,
 				F4353D351AC06F10005A6198 /* GPBDictionaryTests+Int32.m in Sources */,
diff --git a/objectivec/ProtocolBuffers_OSX.xcodeproj/xcshareddata/xcschemes/PerformanceTests.xcscheme b/objectivec/ProtocolBuffers_OSX.xcodeproj/xcshareddata/xcschemes/PerformanceTests.xcscheme
index 2f618131..2883109c 100644
--- a/objectivec/ProtocolBuffers_OSX.xcodeproj/xcshareddata/xcschemes/PerformanceTests.xcscheme
+++ b/objectivec/ProtocolBuffers_OSX.xcodeproj/xcshareddata/xcschemes/PerformanceTests.xcscheme
@@ -51,6 +51,12 @@
                   Identifier = "DescriptorTests">
                </Test>
                <Test
+                  Identifier = "GPBAutocreatedArrayTests">
+               </Test>
+               <Test
+                  Identifier = "GPBAutocreatedDictionaryTests">
+               </Test>
+               <Test
                   Identifier = "GPBBoolArrayTests">
                </Test>
                <Test
@@ -90,6 +96,9 @@
                   Identifier = "GPBEnumArrayTests">
                </Test>
                <Test
+                  Identifier = "GPBExtensionRegistryTest">
+               </Test>
+               <Test
                   Identifier = "GPBFloatArrayTests">
                </Test>
                <Test