[blinkpy] Prepending to sys.path instead of appending

This is a code-health cleanup following discussions in
https://crrev.com/c/1462139/13/chrome/test/chromedriver/test/run_webdriver_tests.py#30

This is a mechanical substitution in blinkpy excluding third_party.

Change-Id: Ib546bb5fea743484186f62fd6fc1ea561700d610
Reviewed-on: https://chromium-review.googlesource.com/c/1473845Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: Robert Ma <robertma@chromium.org>
Cr-Commit-Position: refs/heads/master@{#632380}

third_party/blink/tools/blinkpy/common/path_finder.py

@@ -35,19 +35,19 @@ from blinkpy.common.memoized import memoized
 def add_typ_dir_to_sys_path():
     path_to_typ = get_typ_dir()
     if path_to_typ not in sys.path:
-        sys.path.append(path_to_typ)
+        sys.path.insert(0, path_to_typ)
 
 
 def add_bindings_scripts_dir_to_sys_path():
     path_to_bindings_scripts = get_bindings_scripts_dir()
     if path_to_bindings_scripts not in sys.path:
-        sys.path.append(path_to_bindings_scripts)
+        sys.path.insert(0, path_to_bindings_scripts)
 
 
 def add_blinkpy_thirdparty_dir_to_sys_path():
     path = get_blinkpy_thirdparty_dir()
     if path not in sys.path:
-        sys.path.append(path)
+        sys.path.insert(0, path)
 
 
 def add_depot_tools_dir_to_os_path():
@@ -92,7 +92,7 @@ def get_blink_tools_dir():
 def add_blink_tools_dir_to_sys_path():
     path = get_blink_tools_dir()
     if path not in sys.path:
-        sys.path.append(path)
+        sys.path.insert(0, path)
 
 
 def _does_blink_web_tests_exist():

third_party/blink/tools/blinkpy/common/system/executive_unittest.py

@@ -36,7 +36,7 @@ import unittest
 # ensure that blink/tools is in sys.path for the next imports to work correctly.
 script_dir = os.path.dirname(os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__file__)))))
 if script_dir not in sys.path:
-    sys.path.append(script_dir)
+    sys.path.insert(0, script_dir)
 
 from blinkpy.common.system.executive import Executive, ScriptError
 

third_party/blink/tools/blinkpy/web_tests/controllers/web_test_finder_unittest.py

@@ -12,7 +12,7 @@ from blinkpy.web_tests.controllers import web_test_finder
 
 _MOCK_ROOT = os.path.join(
     path_finder.get_chromium_src_dir(), 'third_party', 'pymock')
-sys.path.append(_MOCK_ROOT)
+sys.path.insert(0, _MOCK_ROOT)
 import mock
 
 

third_party/blink/tools/blinkpy/web_tests/port/android_unittest.py

@@ -43,13 +43,13 @@ from blinkpy.web_tests.port import port_testcase
 
 _DEVIL_ROOT = os.path.join(
     get_chromium_src_dir(), 'third_party', 'catapult', 'devil')
-sys.path.append(_DEVIL_ROOT)
+sys.path.insert(0, _DEVIL_ROOT)
 from devil.android import device_utils
 from devil.android.sdk import adb_wrapper
 
 _MOCK_ROOT = os.path.join(
     get_chromium_src_dir(), 'third_party', 'pymock')
-sys.path.append(_MOCK_ROOT)
+sys.path.insert(0, _MOCK_ROOT)
 import mock
 
 

third_party/blink/tools/blinkpy/web_tests/port/mock_drt.py

@@ -45,7 +45,7 @@ import types
 # that blink/tools is in sys.path for the next imports to work correctly.
 tools_dir = os.path.dirname(os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__file__)))))
 if tools_dir not in sys.path:
-    sys.path.append(tools_dir)
+    sys.path.insert(0, tools_dir)
 
 from blinkpy.common import exit_codes
 from blinkpy.common import read_checksum_from_png

third_party/blink/tools/blinkpy/web_tests/run_web_tests_unittest.py

@@ -51,7 +51,7 @@ from blinkpy.web_tests.views.printing import Printer
 
 _MOCK_ROOT = os.path.join(
     path_finder.get_chromium_src_dir(), 'third_party', 'pymock')
-sys.path.append(_MOCK_ROOT)
+sys.path.insert(0, _MOCK_ROOT)
 import mock