Updated older RETURN syntax to newer one

Author: emanlove

atest/acceptance/locators/custom.robot

@@ -55,4 +55,4 @@ Teardown Custom Locator
 Custom Locator Strategy
     [Arguments]    ${browser}    ${locator}    ${tag}    ${constraints}
     ${element}=    Execute Javascript    return window.document.getElementById('${locator}') || [];
-    [Return]    ${element}
+    RETURN    ${element}

atest/acceptance/resource.robot

@@ -24,7 +24,7 @@ Open Browser To Start Page Without Testing Default Options
     ...    desired_capabilities=${DESIRED_CAPABILITIES}    alias=${alias}
     ${orig speed} =    Set Selenium Speed    ${SPEED}
     ${orig timeout} =    Set Selenium Timeout    10 seconds
-    [Return]    ${orig speed}    5 seconds
+    RETURN    ${orig speed}    5 seconds
 
 Cannot Be Executed In IE
     [Documentation]    Cannot Be Executed In IE

src/SeleniumLibrary/__init__.py

@@ -238,7 +238,7 @@ class SeleniumLibrary(DynamicCore):
 
     | Custom Locator Strategy | [Arguments] | ${browser} | ${locator} | ${tag} | ${constraints} |
     |   | ${element}= | Execute Javascript | return window.document.getElementById('${locator}'); |
-    |   | [Return] | ${element} |
+    |   | RETURN | ${element} |
 
     This keyword is a reimplementation of the basic functionality of the
     ``id`` locator where ``${browser}`` is a reference to a WebDriver

utest/test/api/approved_files/PluginDocumentation.test_many_plugins.approved.txt

@@ -177,7 +177,7 @@ a WebElement that should be acted on:
 
 | Custom Locator Strategy | [Arguments] | ${browser} | ${locator} | ${tag} | ${constraints} |
 |   | ${element}= | Execute Javascript | return window.document.getElementById('${locator}'); |
-|   | [Return] | ${element} |
+|   | RETURN | ${element} |
 
 This keyword is a reimplementation of the basic functionality of the
 ``id`` locator where ``${browser}`` is a reference to a WebDriver