Added compiling the dart code for scenario tests as part of the xcode build (flutter#16937)

Author: gaaclarke

testing/scenario_app/ios/Scenarios/Scenarios.xcodeproj/project.pbxproj

@@ -297,6 +297,7 @@
 			isa = PBXNativeTarget;
 			buildConfigurationList = 248D76F322E388380012F0C1 /* Build configuration list for PBXNativeTarget "Scenarios" */;
 			buildPhases = (
+				0D8470A8241035AD0030B565 /* Compile iOS JIT */,
 				248D76C322E388370012F0C1 /* Sources */,
 				248D76C422E388370012F0C1 /* Frameworks */,
 				248D76C522E388370012F0C1 /* Resources */,
@@ -439,6 +440,27 @@
 		};
 /* End PBXResourcesBuildPhase section */
 
+/* Begin PBXShellScriptBuildPhase section */
+		0D8470A8241035AD0030B565 /* Compile iOS JIT */ = {
+			isa = PBXShellScriptBuildPhase;
+			buildActionMask = 2147483647;
+			files = (
+			);
+			inputFileListPaths = (
+			);
+			inputPaths = (
+			);
+			name = "Compile iOS JIT";
+			outputFileListPaths = (
+			);
+			outputPaths = (
+			);
+			runOnlyForDeploymentPostprocessing = 0;
+			shellPath = /bin/sh;
+			shellScript = "set -e\ncd ../..\nif [ -z ${FLUTTER_ENGINE+x} ]; then \n  FLUTTER_ENGINE=ios_debug_sim_unopt\nfi\n./compile_ios_jit.sh ../../../out/host_debug_unopt ../../../out/$FLUTTER_ENGINE/clang_x64\n";
+		};
+/* End PBXShellScriptBuildPhase section */
+
 /* Begin PBXSourcesBuildPhase section */
 		248D76C322E388370012F0C1 /* Sources */ = {
 			isa = PBXSourcesBuildPhase;

testing/scenario_app/run_ios_tests.sh

@@ -15,8 +15,6 @@ fi
 
 cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd
 
-./compile_ios_jit.sh ../../../out/host_debug_unopt ../../../out/$FLUTTER_ENGINE/clang_x64
-
 pushd ios/Scenarios
 
 set -o pipefail && xcodebuild -sdk iphonesimulator \