Add new relocation type WASM_MEMORY_SIZE_REFERENCE, use relocatable pointers to update wasm memory size references in generated code.
 - Add new RelocInfo mode WASM_MEMORY_SIZE_REFERENCE in the assembler and add relocation information to immediates in compare instructions.
 - Use relocatable constants for MemSize/BoundsCheck in the wasm compiler

R=titzer@chromium.org, yangguo@chromium.org, bradnelson@chromium.org

Review-Url: https://codereview.chromium.org/1921203002
Cr-Commit-Position: refs/heads/master@{#36044}