Add an env var to force devtools_tool to use SDKs from PATH

tool/bin/devtools_tool

@@ -1,3 +1,11 @@
 #!/bin/bash -e
+
 SCRIPT_DIR=$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )
-"$SCRIPT_DIR/../flutter-sdk/bin/dart" run "$SCRIPT_DIR/devtools_tool.dart" "$@"
+
+if [ ! -z "$DEVTOOLS_TOOL_FLUTTER_FROM_PATH" ]
+then
+	echo Running devtools_tool using Dart/Flutter from PATH because DEVTOOLS_TOOL_FLUTTER_FROM_PATH is set
+	dart run "$SCRIPT_DIR/devtools_tool.dart" "$@"
+else
+	"$SCRIPT_DIR/../flutter-sdk/bin/dart" run "$SCRIPT_DIR/devtools_tool.dart" "$@"
+fi

tool/bin/devtools_tool.bat

@@ -1,5 +1,10 @@
 @echo off
 
-%~dp0/../flutter-sdk/bin/dart run %~dp0/devtools_tool.dart %*
+IF DEFINED DEVTOOLS_TOOL_FLUTTER_FROM_PATH (
+	echo Running devtools_tool using Dart/Flutter from PATH because DEVTOOLS_TOOL_FLUTTER_FROM_PATH is set
+	dart run %~dp0/devtools_tool.dart %*
+) ELSE (
+	%~dp0/../flutter-sdk/bin/dart run %~dp0/devtools_tool.dart %*
+)
 
 EXIT /B %errorlevel%

tool/flutter_customer_tests/setup.sh

@@ -6,6 +6,8 @@
 root_dir=$(pwd)
 tool_dir="$root_dir/tool/bin"
 export PATH=$PATH:$tool_dir
+# Force devtools_tool to use the current Flutter (which is available on PATH).
+export DEVTOOLS_TOOL_FLUTTER_FROM_PATH=true
 cd tool
 flutter pub get
 devtools_tool pub-get