MIPS64: Fix sim stack-printing and tweak reg dumps.

The stack printing used 32-bit values, and needed to be fixed.
The register dump change was just print formatting, still not
sure it is optimal.
MIPS64: Fix PatchRelocatedValue with new li 64-bit value.
Merge remote-tracking branch 'origin/pl-mips64' into yy-dev-mips64
MIPS64: Remove all break_ and fix InstanceofStub/DoStoreNamedField/DoStoreKeyedFixedArray.
MIPS64: Add ddiv to simulator.

Some test like mjsunit/apply will call ddiv.
MIPS64: Representation fix for DoStoreKeyedFixedArray().

TEST: mjsunit/regress/external-and-normal-array-polymorphism
MIPS64: String length fixed in EnsureNotWhite().
MIPS64: Add a TODO.