Improve Dictionary Initialize CQ

[benaadams]

Total bytes of diff: -3316 (-0.10% of base)
    diff is an improvement.

Total byte diff includes 0 bytes from reconciling methods
        Base had    0 unique methods,        0 unique bytes
        Diff had    0 unique methods,        0 unique bytes

Top file improvements by size (bytes):
       -3316 : System.Private.CoreLib.dasm (-0.10% of base)

1 total files with size differences (1 improved, 0 regressed), 0 unchanged.

Top method improvements by size (bytes):
       -3142 : System.Private.CoreLib.dasm - Dictionary`2:OnDeserialization(ref):this (29 methods)
        -174 : System.Private.CoreLib.dasm - Dictionary`2:Initialize(int):this (29 methods)

2 total methods with size differences (2 improved, 0 regressed), 16743 unchanged.

[jkotas]

Thanks