Avoid excessive newlines for short variable names with --aosp

I'm trying this out in chromium codebase, and besides the known-issue of excessive lambda whitespace (issue #19), I'm finding the most jarring thing is odd whitespace for variable assignments.

google-java-format does:

```
desc =
getResources()
.getString(R.string.cablev2_error_ble_permission, packageLabel);
```

instead of:
```
desc = getResources()
.getString(R.string.cablev2_error_ble_permission, packageLabel);
```

I'm guessing it might be because with two space indents, the wrapped line appears under the = sign (which looks less weird), but with four space indent, it looks really odd

首先定位在 --aosp 下处理变量赋值和换行的 formatter 逻辑。然后找到相关的格式化测试，添加一个与此处所示短名称赋值相匹配的用例，并确认输出按要求将赋值表达式保持在一起。

由索引模型根据 Issue 内容生成。