Can't have negative floats

Description of the bug:

Tried to subtract a float from a float, or have a negative float, and it errored out.

What did you do, or what's a simple way to reproduce the bug?

https://carbon.compiler-explorer.com/z/fPGeeqvj8

What did you expect to happen?

Have a negative value, or do subtraction.

What actually happened?

:8:55: error: cannot access member of interface Core.Negate in type Core.FloatLiteral that does not implement that interface var ne_point: AnInitializeablePoint = {.x = 1.0, .y = -1.0}; ^~~~

:9:46: error: cannot access member of interface Core.SubWith(Core.FloatLiteral) in type Core.FloatLiteral that does not implement that interface var sw_point: AnInitializeablePoint = {.x = (0.0 - 1.0), .y = 1.0}; ^~~~~~~~~

Any other information, logs, or outputs that you want to share?

class AnInitializeablePoint {
 var x: f64;
 var y: f64;
}

var ne_point: AnInitializeablePoint = {.x = 1.0, .y = -1.0};
var sw_point: AnInitializeablePoint = {.x = (0.0 - 1.0), .y = 1.0};