Introduce IKG into kernel-service to support incremental compilation.

runtime/vm/dart_api_impl.cc

Index: runtime/vm/dart_api_impl.cc
diff --git a/runtime/vm/dart_api_impl.cc b/runtime/vm/dart_api_impl.cc
index 4bc1125f23058b732b486cee122f850f03dd89db..f02da77da38680860a5659751abef9f341ded32f 100644
--- a/runtime/vm/dart_api_impl.cc
+++ b/runtime/vm/dart_api_impl.cc
@@ -5868,21 +5868,38 @@ Dart_CompileToKernel(const char* script_uri) {
 #endif
 }
 
-DART_EXPORT Dart_KernelCompilationResult
-Dart_CompileSourcesToKernel(const char* script_uri,
-                            int source_files_count,
-                            Dart_SourceFile sources[]) {
+static Dart_KernelCompilationResult CompileSourcesToKernel(
+    const char* script_uri,
+    int source_files_count,
+    Dart_SourceFile sources[],
+    bool incremental) {
 #ifdef DART_PRECOMPILED_RUNTIME
   Dart_KernelCompilationResult result;
   result.status = Dart_KernelCompilationStatus_Unknown;
   result.error = strdup("Dart_CompileSourcesToKernel is unsupported.");
   return result;
 #else
-  return KernelIsolate::CompileToKernel(script_uri, source_files_count,
-                                        sources);
+  return KernelIsolate::CompileToKernel(script_uri, source_files_count, sources,
+                                        incremental);
 #endif
 }
 
+DART_EXPORT Dart_KernelCompilationResult
+Dart_CompileSourcesToKernel(const char* script_uri,
+                            int source_files_count,
+                            Dart_SourceFile sources[]) {
+  return CompileSourcesToKernel(script_uri, source_files_count, sources,
+                                false /* incremental */);
+}
+
+DART_EXPORT Dart_KernelCompilationResult
+Dart_IncrementallyCompileSourcesToKernel(const char* script_uri,
+                                         int source_files_count,
+                                         Dart_SourceFile sources[]) {
+  return CompileSourcesToKernel(script_uri, source_files_count, sources,
+                                true /* incremental */);
+}
+
 // --- Service support ---
 
 DART_EXPORT bool Dart_IsServiceIsolate(Dart_Isolate isolate) {