Fix spew when running presubmit which triggers dartfmt.bat on windows. We should also backport this change to the sdks in tools/sdk or roll a new version of the tools/sdk

Error span you otherwise get with each dartfmt invocation:

find: ‘>     bin [’: No such file or directory

Note that the error doesn't occur all times dartfmt is run, only when it is
run from the directory triggered by the presubmit.

BUG=
R=rnystrom@google.com, whesse@google.com

Review-Url: https://codereview.chromium.org/2759333004 .

sdk/bin/dart2js.bat

@@ -50,7 +50,7 @@ setlocal
 for %%i in (%1) do set result=%%~fi
 set current=
 for /f "usebackq tokens=2 delims=[]" %%i in (`dir /a:l "%~dp1" 2^>nul ^
-                                             ^| %SystemRoot%\System32\find.exe ">     %~n1 ["`) do (
+                                             ^| %SystemRoot%\System32\find.exe ">     %~n1 [" 2^>nul`) do (
   set current=%%i
 )
 if not "%current%"=="" call :follow_links "%current%", result

sdk/bin/dart2js_sdk.bat

@@ -47,7 +47,7 @@ setlocal
 for %%i in (%1) do set result=%%~fi
 set current=
 for /f "usebackq tokens=2 delims=[]" %%i in (`dir /a:l "%~dp1" 2^>nul ^
-                                             ^| find ">     %~n1 ["`) do (
+                                             ^| find ">     %~n1 [" 2^>nul`) do (
   set current=%%i
 )
 if not "%current%"=="" call :follow_links "%current%", result

sdk/bin/dartanalyzer.bat

@@ -60,7 +60,7 @@ setlocal
 for %%i in (%1) do set result=%%~fi
 set current=
 for /f "usebackq tokens=2 delims=[]" %%i in (`dir /a:l "%~dp1" 2^>nul ^
-                                             ^| %SystemRoot%\System32\find.exe ">     %~n1 ["`) do (
+                                             ^| %SystemRoot%\System32\find.exe ">     %~n1 [" 2^>nul`) do (
   set current=%%i
 )
 if not "%current%"=="" call :follow_links "%current%", result

sdk/bin/dartanalyzer_sdk.bat

@@ -42,7 +42,7 @@ setlocal
 for %%i in (%1) do set result=%%~fi
 set current=
 for /f "usebackq tokens=2 delims=[]" %%i in (`dir /a:l "%~dp1" 2^>nul ^
-                                             ^| find ">     %~n1 ["`) do (
+                                             ^| find ">     %~n1 [" 2^>nul`) do (
   set current=%%i
 )
 if not "%current%"=="" call :follow_links "%current%", result

sdk/bin/dartdevc.bat

@@ -56,7 +56,7 @@ setlocal
 for %%i in (%1) do set result=%%~fi
 set current=
 for /f "usebackq tokens=2 delims=[]" %%i in (`dir /a:l "%~dp1" 2^>nul ^
-                                             ^| find ">     %~n1 ["`) do (
+                                             ^| find ">     %~n1 [" 2^>nul`) do (
   set current=%%i
 )
 if not "%current%"=="" call :follow_links "%current%", result

sdk/bin/dartdoc.bat

@@ -34,7 +34,7 @@ setlocal
 for %%i in (%1) do set result=%%~fi
 set current=
 for /f "usebackq tokens=2 delims=[]" %%i in (`dir /a:l "%~dp1" 2^>nul ^
-                                             ^| %SystemRoot%\System32\find.exe ">     %~n1 ["`) do (
+                                             ^| %SystemRoot%\System32\find.exe ">     %~n1 [" 2^>nul`) do (
   set current=%%i
 )
 if not "%current%"=="" call :follow_links "%current%", result

sdk/bin/dartfmt.bat

@@ -47,7 +47,7 @@ setlocal
 for %%i in (%1) do set result=%%~fi
 set current=
 for /f "usebackq tokens=2 delims=[]" %%i in (`dir /a:l "%~dp1" 2^>nul ^
-                                             ^| %SystemRoot%\System32\find.exe ">     %~n1 ["`) do (
+                                             ^| %SystemRoot%\System32\find.exe ">     %~n1 [" 2^>nul`) do (
   set current=%%i
 )
 if not "%current%"=="" call :follow_links "%current%", result

sdk/bin/pub.bat

@@ -46,7 +46,7 @@ setlocal
 for %%i in (%1) do set result=%%~fi
 set current=
 for /f "usebackq tokens=2 delims=[]" %%i in (`dir /a:l "%~dp1" 2^>nul ^
-                                             ^| %SystemRoot%\System32\find.exe ">     %~n1 ["`) do (
+                                             ^| %SystemRoot%\System32\find.exe ">     %~n1 [" 2^>nul`) do (
   set current=%%i
 )
 if not "%current%"=="" call :follow_links "%current%", result

sdk/bin/pub_sdk.bat

@@ -35,7 +35,7 @@ setlocal
 for %%i in (%1) do set result=%%~fi
 set current=
 for /f "usebackq tokens=2 delims=[]" %%i in (`dir /a:l "%~dp1" 2^>nul ^
-                                             ^| find ">     %~n1 ["`) do (
+                                             ^| find ">     %~n1 [" 2^>nul`) do (
   set current=%%i
 )
 if not "%current%"=="" call :follow_links "%current%", result