## 🐛 Bug Report

I cannot retrieve the firefox console logs, I get the following JsonException when I try to do so:
```
Exception in thread "main" org.openqa.selenium.json.JsonException: Unable to determine type from: H. Last 1 characters read: H
Build info: version: '3.141.59', revision: 'e82be7d358', time: '2018-11-14T08:17:03'
System info: host: 'vivat', ip: '127.0.0.1', os.name: 'Linux', os.arch: 'amd64', os.version: '5.3.10-arch1-1', java.version: '1.8.0_232'
Driver info: driver.version: RemoteWebDriver
	at org.openqa.selenium.json.JsonInput.peek(JsonInput.java:122)
	at org.openqa.selenium.json.JsonTypeCoercer.lambda$null$6(JsonTypeCoercer.java:140)
	at org.openqa.selenium.json.JsonTypeCoercer.coerce(JsonTypeCoercer.java:126)
	at org.openqa.selenium.json.Json.toType(Json.java:69)
	at org.openqa.selenium.json.Json.toType(Json.java:55)
	at org.openqa.selenium.json.Json.toType(Json.java:50)
	at org.openqa.selenium.remote.http.W3CHttpResponseCodec.decode(W3CHttpResponseCodec.java:87)
	at org.openqa.selenium.remote.http.W3CHttpResponseCodec.decode(W3CHttpResponseCodec.java:49)
	at org.openqa.selenium.remote.HttpCommandExecutor.execute(HttpCommandExecutor.java:158)
	at org.openqa.selenium.remote.service.DriverCommandExecutor.execute(DriverCommandExecutor.java:83)
	at org.openqa.selenium.remote.RemoteWebDriver.execute(RemoteWebDriver.java:552)
	at org.openqa.selenium.remote.RemoteExecuteMethod.execute(RemoteExecuteMethod.java:35)
	at org.openqa.selenium.remote.RemoteLogs.getRemoteEntries(RemoteLogs.java:81)
	at org.openqa.selenium.remote.RemoteLogs.get(RemoteLogs.java:77)

```

After debugging on W3CHttpResponseCode#decode, it seems that the exception is thrown because the content of the response is not a JSON but a text/plain that only contains "HTTP method not allowed". 

When checking what request has been sent, it seems that the following POST request is performed:
> POST /session/81a0b1fc-cc58-468e-9976-3d783c18f1db/log

So I guess there is two issues:
  - the command is wrong for Firefox
  - the error is not parsed correctly

I don't reproduce on Chrome, only on Firefox.

## To Reproduce

Here's the Java method I'm using to reproduce:

```
// GeckoDriver v0.26.0
System.setProperty("webdriver.gecko.driver", "/home/urli/geckodriver/geckodriver");
FirefoxOptions firefoxOptions = new FirefoxOptions();
LoggingPreferences logPrefs = new LoggingPreferences();
logPrefs.enable(LogType.BROWSER, Level.ALL);

firefoxOptions.setCapability(CapabilityType.LOGGING_PREFS, logPrefs);

WebDriver driver = new FirefoxDriver(firefoxOptions);
driver.get("https://developer.mozilla.org/fr/docs/Web/API/console");
for (LogEntry logEntry : driver.manage().logs().get(LogType.BROWSER)) {
   System.out.println(String.format("[%s] [%s]", logEntry.getLevel(), logEntry.getMessage()));
}
driver.quit();
```

Detailed steps to reproduce the behavior:

## Expected behavior

I expect to see the browser console logs.

## Environment

OS: ArchLinux
Browser: Firefox
Browser version: 70.0.1
Browser Driver version: GeckoDriver 0.26.0
Language Bindings version: Java 3.141.59

import org.openqa.selenium.UnhandledAlertException;
import org.openqa.selenium.WebDriverException;
import org.openqa.selenium.json.Json;
import org.openqa.selenium.remote.ErrorCodes;
import org.openqa.selenium.remote.Response;
import org.openqa.selenium.remote.codec.AbstractHttpResponseCodec;
import org.openqa.selenium.remote.http.HttpResponse;
import org.openqa.selenium.remote.JsonToWebElementConverter;
import java.lang.reflect.Constructor;
import java.util.HashMap;
import java.util.Map;
import java.util.Optional;
import java.util.function.Function;
import java.util.logging.Logger;
/**
 * A response codec that adheres to the W3C WebDriver wire protocol.
 *
 * @see <a href="https:w3.org/tr/webdriver">W3C WebDriver spec</a>
 */
public class W3CHttpResponseCodec extends AbstractHttpResponseCodec {